[v2,2/3] audio: use object link instead of qdev property to pass wm8750 reference

Message ID 20181012083008.29027-3-maozhongyi@cmss.chinamobile.com
State New
Headers show
Series
  • use object link instead of qdev property
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Commit Message

Mao Zhongyi Oct. 12, 2018, 8:30 a.m.
According to qdev-properties.h, properties of pointer type should
be avoided, it seems a link type property is a good substitution.

Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
To: qemu-arm@nongnu.org

Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
---
 hw/arm/musicpal.c          |  3 ++-
 hw/audio/marvell_88w8618.c | 14 ++++++--------
 2 files changed, 8 insertions(+), 9 deletions(-)

Comments

Philippe Mathieu-Daudé Oct. 12, 2018, 9:53 a.m. | #1
Hi Mao,

On 12/10/2018 10:30, Mao Zhongyi wrote:
> According to qdev-properties.h, properties of pointer type should
> be avoided, it seems a link type property is a good substitution.
> 
> Cc: Jan Kiszka <jan.kiszka@web.de>
> Cc: Peter Maydell <peter.maydell@linaro.org>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> To: qemu-arm@nongnu.org
> 
> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
> ---
>  hw/arm/musicpal.c          |  3 ++-
>  hw/audio/marvell_88w8618.c | 14 ++++++--------
>  2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
> index 3dafb41b0b..ac266f9253 100644
> --- a/hw/arm/musicpal.c
> +++ b/hw/arm/musicpal.c
> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>      wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>      dev = qdev_create(NULL, "mv88w8618_audio");
>      s = SYS_BUS_DEVICE(dev);
> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
> +                             TYPE_WM8750, NULL);
>      qdev_init_nofail(dev);
>      sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>      sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
> index cf6ce6979b..baab4a3d53 100644
> --- a/hw/audio/marvell_88w8618.c
> +++ b/hw/audio/marvell_88w8618.c
> @@ -15,6 +15,7 @@
>  #include "hw/i2c/i2c.h"
>  #include "hw/audio/wm8750.h"
>  #include "audio/audio.h"
> +#include "qapi/error.h"
>  
>  #define MP_AUDIO_SIZE           0x00001000
>  
> @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>      memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>                            "audio", MP_AUDIO_SIZE);
>      sysbus_init_mmio(dev, &s->iomem);
> +
> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
> +                             (Object **) &s->wm,
> +                             qdev_prop_allow_set_link_before_realize,
> +                             0, &error_abort);
>  }
>  
>  static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
> @@ -279,11 +285,6 @@ static const VMStateDescription mv88w8618_audio_vmsd = {
>      }
>  };
>  
> -static Property mv88w8618_audio_properties[] = {
> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
> -    {/* end of list */},
> -};
> -
>  static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -291,9 +292,6 @@ static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>      dc->realize = mv88w8618_audio_realize;
>      dc->reset = mv88w8618_audio_reset;
>      dc->vmsd = &mv88w8618_audio_vmsd;
> -    dc->props = mv88w8618_audio_properties;
> -    /* Reason: pointer property "wm8750" */
> -    dc->user_creatable = false;

Having a link property isn't it the same restriction?

>  }
>  
>  static const TypeInfo mv88w8618_audio_info = {
>
Mao Zhongyi Oct. 12, 2018, 11:51 a.m. | #2
Hi, Philippe

On 10/12/18 5:53 PM, Philippe Mathieu-Daudé wrote:
> Hi Mao,
> 
> On 12/10/2018 10:30, Mao Zhongyi wrote:
>> According to qdev-properties.h, properties of pointer type should
>> be avoided, it seems a link type property is a good substitution.
>>
>> Cc: Jan Kiszka <jan.kiszka@web.de>
>> Cc: Peter Maydell <peter.maydell@linaro.org>
>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>> To: qemu-arm@nongnu.org
>>
>> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
>> ---
>>   hw/arm/musicpal.c          |  3 ++-
>>   hw/audio/marvell_88w8618.c | 14 ++++++--------
>>   2 files changed, 8 insertions(+), 9 deletions(-)
>>
>> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
>> index 3dafb41b0b..ac266f9253 100644
>> --- a/hw/arm/musicpal.c
>> +++ b/hw/arm/musicpal.c
>> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>>       wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>>       dev = qdev_create(NULL, "mv88w8618_audio");
>>       s = SYS_BUS_DEVICE(dev);
>> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
>> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
>> +                             TYPE_WM8750, NULL);
>>       qdev_init_nofail(dev);
>>       sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>>       sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
>> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
>> index cf6ce6979b..baab4a3d53 100644
>> --- a/hw/audio/marvell_88w8618.c
>> +++ b/hw/audio/marvell_88w8618.c
>> @@ -15,6 +15,7 @@
>>   #include "hw/i2c/i2c.h"
>>   #include "hw/audio/wm8750.h"
>>   #include "audio/audio.h"
>> +#include "qapi/error.h"
>>   
>>   #define MP_AUDIO_SIZE           0x00001000
>>   
>> @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>>       memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>>                             "audio", MP_AUDIO_SIZE);
>>       sysbus_init_mmio(dev, &s->iomem);
>> +
>> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
>> +                             (Object **) &s->wm,
>> +                             qdev_prop_allow_set_link_before_realize,
>> +                             0, &error_abort);
>>   }
>>   
>>   static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>> @@ -279,11 +285,6 @@ static const VMStateDescription mv88w8618_audio_vmsd = {
>>       }
>>   };
>>   
>> -static Property mv88w8618_audio_properties[] = {
>> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
>> -    {/* end of list */},
>> -};
>> -
>>   static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>   {
>>       DeviceClass *dc = DEVICE_CLASS(klass);
>> @@ -291,9 +292,6 @@ static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>       dc->realize = mv88w8618_audio_realize;
>>       dc->reset = mv88w8618_audio_reset;
>>       dc->vmsd = &mv88w8618_audio_vmsd;
>> -    dc->props = mv88w8618_audio_properties;
>> -    /* Reason: pointer property "wm8750" */
>> -    dc->user_creatable = false;
> 
> Having a link property isn't it the same restriction?

This task can found in 
https://wiki.qemu.org/Contribute/BiteSizedTasks#Device_models

Convert qdev pointer properties (defined with DEFINE_PROP_PTR) to QOM 
links. Example: commit 873b4d3.

Thanks,
Mao

> 
>>   }
>>   
>>   static const TypeInfo mv88w8618_audio_info = {
>>
>
Philippe Mathieu-Daudé Oct. 12, 2018, 12:30 p.m. | #3
Cc'ing Eduardo and Thomas.

On 12/10/2018 13:51, maozy wrote:
> Hi, Philippe
> 
> On 10/12/18 5:53 PM, Philippe Mathieu-Daudé wrote:
>> Hi Mao,
>>
>> On 12/10/2018 10:30, Mao Zhongyi wrote:
>>> According to qdev-properties.h, properties of pointer type should
>>> be avoided, it seems a link type property is a good substitution.
>>>
>>> Cc: Jan Kiszka <jan.kiszka@web.de>
>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>> To: qemu-arm@nongnu.org
>>>
>>> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
>>> ---
>>>   hw/arm/musicpal.c          |  3 ++-
>>>   hw/audio/marvell_88w8618.c | 14 ++++++--------
>>>   2 files changed, 8 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
>>> index 3dafb41b0b..ac266f9253 100644
>>> --- a/hw/arm/musicpal.c
>>> +++ b/hw/arm/musicpal.c
>>> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>>>       wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>>>       dev = qdev_create(NULL, "mv88w8618_audio");
>>>       s = SYS_BUS_DEVICE(dev);
>>> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
>>> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
>>> +                             TYPE_WM8750, NULL);
>>>       qdev_init_nofail(dev);
>>>       sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>>>       sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
>>> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
>>> index cf6ce6979b..baab4a3d53 100644
>>> --- a/hw/audio/marvell_88w8618.c
>>> +++ b/hw/audio/marvell_88w8618.c
>>> @@ -15,6 +15,7 @@
>>>   #include "hw/i2c/i2c.h"
>>>   #include "hw/audio/wm8750.h"
>>>   #include "audio/audio.h"
>>> +#include "qapi/error.h"
>>>     #define MP_AUDIO_SIZE           0x00001000
>>>   @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>>>       memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>>>                             "audio", MP_AUDIO_SIZE);
>>>       sysbus_init_mmio(dev, &s->iomem);
>>> +
>>> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
>>> +                             (Object **) &s->wm,
>>> +                             qdev_prop_allow_set_link_before_realize,
>>> +                             0, &error_abort);
>>>   }
>>>     static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>>> @@ -279,11 +285,6 @@ static const VMStateDescription
>>> mv88w8618_audio_vmsd = {
>>>       }
>>>   };
>>>   -static Property mv88w8618_audio_properties[] = {
>>> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
>>> -    {/* end of list */},
>>> -};
>>> -
>>>   static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>   {
>>>       DeviceClass *dc = DEVICE_CLASS(klass);
>>> @@ -291,9 +292,6 @@ static void
>>> mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>       dc->realize = mv88w8618_audio_realize;
>>>       dc->reset = mv88w8618_audio_reset;
>>>       dc->vmsd = &mv88w8618_audio_vmsd;
>>> -    dc->props = mv88w8618_audio_properties;
>>> -    /* Reason: pointer property "wm8750" */
>>> -    dc->user_creatable = false;
>>
>> Having a link property isn't it the same restriction?
> 
> This task can found in
> https://wiki.qemu.org/Contribute/BiteSizedTasks#Device_models
> 
> Convert qdev pointer properties (defined with DEFINE_PROP_PTR) to QOM
> links. Example: commit 873b4d3.

I agree with the QOM conversion (the rest of this patch), what I'm
wondering is if declaring this device now user_creatable is correct. I
don't think we can set link property from command line, but maybe I'm
wrong because I never investigate/tried to do it.

Maybe devices having link property are automatically marked as
user_creatable = false, then your change would be correct (except you
should explicit that in the commit message).

I'll post another mail on the list to ask about that.

Regards,

Phil.

> 
> Thanks,
> Mao
> 
>>
>>>   }
>>>     static const TypeInfo mv88w8618_audio_info = {
>>>
>>
> 
>
Philippe Mathieu-Daudé Oct. 12, 2018, 6:40 p.m. | #4
Hi Mao,

On 12/10/2018 14:30, Philippe Mathieu-Daudé wrote:
> Cc'ing Eduardo and Thomas.
> 
> On 12/10/2018 13:51, maozy wrote:
>> Hi, Philippe
>>
>> On 10/12/18 5:53 PM, Philippe Mathieu-Daudé wrote:
>>> Hi Mao,
>>>
>>> On 12/10/2018 10:30, Mao Zhongyi wrote:
>>>> According to qdev-properties.h, properties of pointer type should
>>>> be avoided, it seems a link type property is a good substitution.
>>>>
>>>> Cc: Jan Kiszka <jan.kiszka@web.de>
>>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>>> To: qemu-arm@nongnu.org
>>>>
>>>> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
>>>> ---
>>>>   hw/arm/musicpal.c          |  3 ++-
>>>>   hw/audio/marvell_88w8618.c | 14 ++++++--------
>>>>   2 files changed, 8 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
>>>> index 3dafb41b0b..ac266f9253 100644
>>>> --- a/hw/arm/musicpal.c
>>>> +++ b/hw/arm/musicpal.c
>>>> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>>>>       wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>>>>       dev = qdev_create(NULL, "mv88w8618_audio");
>>>>       s = SYS_BUS_DEVICE(dev);
>>>> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
>>>> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
>>>> +                             TYPE_WM8750, NULL);
>>>>       qdev_init_nofail(dev);
>>>>       sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>>>>       sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
>>>> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
>>>> index cf6ce6979b..baab4a3d53 100644
>>>> --- a/hw/audio/marvell_88w8618.c
>>>> +++ b/hw/audio/marvell_88w8618.c
>>>> @@ -15,6 +15,7 @@
>>>>   #include "hw/i2c/i2c.h"
>>>>   #include "hw/audio/wm8750.h"
>>>>   #include "audio/audio.h"
>>>> +#include "qapi/error.h"
>>>>     #define MP_AUDIO_SIZE           0x00001000
>>>>   @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>>>>       memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>>>>                             "audio", MP_AUDIO_SIZE);
>>>>       sysbus_init_mmio(dev, &s->iomem);
>>>> +
>>>> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
>>>> +                             (Object **) &s->wm,
>>>> +                             qdev_prop_allow_set_link_before_realize,
>>>> +                             0, &error_abort);
>>>>   }
>>>>     static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>>>> @@ -279,11 +285,6 @@ static const VMStateDescription
>>>> mv88w8618_audio_vmsd = {
>>>>       }
>>>>   };
>>>>   -static Property mv88w8618_audio_properties[] = {
>>>> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
>>>> -    {/* end of list */},
>>>> -};
>>>> -
>>>>   static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>>   {
>>>>       DeviceClass *dc = DEVICE_CLASS(klass);
>>>> @@ -291,9 +292,6 @@ static void
>>>> mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>>       dc->realize = mv88w8618_audio_realize;
>>>>       dc->reset = mv88w8618_audio_reset;
>>>>       dc->vmsd = &mv88w8618_audio_vmsd;
>>>> -    dc->props = mv88w8618_audio_properties;
>>>> -    /* Reason: pointer property "wm8750" */
>>>> -    dc->user_creatable = false;
>>>
>>> Having a link property isn't it the same restriction?
>>
>> This task can found in
>> https://wiki.qemu.org/Contribute/BiteSizedTasks#Device_models
>>
>> Convert qdev pointer properties (defined with DEFINE_PROP_PTR) to QOM
>> links. Example: commit 873b4d3.
> 
> I agree with the QOM conversion (the rest of this patch), what I'm
> wondering is if declaring this device now user_creatable is correct. I
> don't think we can set link property from command line, but maybe I'm
> wrong because I never investigate/tried to do it.
> 
> Maybe devices having link property are automatically marked as
> user_creatable = false, then your change would be correct (except you
> should explicit that in the commit message).
> 
> I'll post another mail on the list to ask about that.

On https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg02531.html

Peter answered:

  I think whether a device with a link property is
  user creatable might depend on what the property is
  for and whether the device has a useful fallback for
  "link not connected".

So if you look the realize function, there is no check on the linked object:

    static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
    {
        mv88w8618_audio_state *s = MV88W8618_AUDIO(dev);

        wm8750_data_req_set(s->wm, mv88w8618_audio_callback, s);
    }

Then the called function dereference the WM8750State:

    void wm8750_data_req_set(DeviceState *dev, data_req_cb *data_req,
                             void *opaque)
    {
        WM8750State *s = WM8750(dev);

        s->data_req = data_req;
        s->opaque = opaque;
    }

So this patch is incorrect. You should either keep the
'dc->user_creatable = false' line, or add a check in the realize()
function, as here:

    static void bcm2836_realize(DeviceState *dev, Error **errp)
    {
        Object *obj;
        Error *err = NULL;

        obj = object_property_get_link(OBJECT(dev), "ram", &err);
        if (obj == NULL) {
            error_setg(errp, "%s: required ram link not found: %s",
                       __func__, error_get_pretty(err));
            return;
        }
        ...

Regards,

Phil.

> 
> Regards,
> 
> Phil.
> 
>>
>> Thanks,
>> Mao
>>
>>>
>>>>   }
>>>>     static const TypeInfo mv88w8618_audio_info = {
>>>>
>>>
>>
>>
Mao Zhongyi Oct. 15, 2018, 2:14 a.m. | #5
Hi, Philippe

On 10/13/18 2:40 AM, Philippe Mathieu-Daudé wrote:
> Hi Mao,
> 
> On 12/10/2018 14:30, Philippe Mathieu-Daudé wrote:
>> Cc'ing Eduardo and Thomas.
>>
>> On 12/10/2018 13:51, maozy wrote:
>>> Hi, Philippe
>>>
>>> On 10/12/18 5:53 PM, Philippe Mathieu-Daudé wrote:
>>>> Hi Mao,
>>>>
>>>> On 12/10/2018 10:30, Mao Zhongyi wrote:
>>>>> According to qdev-properties.h, properties of pointer type should
>>>>> be avoided, it seems a link type property is a good substitution.
>>>>>
>>>>> Cc: Jan Kiszka <jan.kiszka@web.de>
>>>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>>>> To: qemu-arm@nongnu.org
>>>>>
>>>>> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
>>>>> ---
>>>>>    hw/arm/musicpal.c          |  3 ++-
>>>>>    hw/audio/marvell_88w8618.c | 14 ++++++--------
>>>>>    2 files changed, 8 insertions(+), 9 deletions(-)
>>>>>
>>>>> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
>>>>> index 3dafb41b0b..ac266f9253 100644
>>>>> --- a/hw/arm/musicpal.c
>>>>> +++ b/hw/arm/musicpal.c
>>>>> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>>>>>        wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>>>>>        dev = qdev_create(NULL, "mv88w8618_audio");
>>>>>        s = SYS_BUS_DEVICE(dev);
>>>>> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
>>>>> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
>>>>> +                             TYPE_WM8750, NULL);
>>>>>        qdev_init_nofail(dev);
>>>>>        sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>>>>>        sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
>>>>> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
>>>>> index cf6ce6979b..baab4a3d53 100644
>>>>> --- a/hw/audio/marvell_88w8618.c
>>>>> +++ b/hw/audio/marvell_88w8618.c
>>>>> @@ -15,6 +15,7 @@
>>>>>    #include "hw/i2c/i2c.h"
>>>>>    #include "hw/audio/wm8750.h"
>>>>>    #include "audio/audio.h"
>>>>> +#include "qapi/error.h"
>>>>>      #define MP_AUDIO_SIZE           0x00001000
>>>>>    @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>>>>>        memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>>>>>                              "audio", MP_AUDIO_SIZE);
>>>>>        sysbus_init_mmio(dev, &s->iomem);
>>>>> +
>>>>> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
>>>>> +                             (Object **) &s->wm,
>>>>> +                             qdev_prop_allow_set_link_before_realize,
>>>>> +                             0, &error_abort);
>>>>>    }
>>>>>      static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>>>>> @@ -279,11 +285,6 @@ static const VMStateDescription
>>>>> mv88w8618_audio_vmsd = {
>>>>>        }
>>>>>    };
>>>>>    -static Property mv88w8618_audio_properties[] = {
>>>>> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
>>>>> -    {/* end of list */},
>>>>> -};
>>>>> -
>>>>>    static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>>>    {
>>>>>        DeviceClass *dc = DEVICE_CLASS(klass);
>>>>> @@ -291,9 +292,6 @@ static void
>>>>> mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>>>        dc->realize = mv88w8618_audio_realize;
>>>>>        dc->reset = mv88w8618_audio_reset;
>>>>>        dc->vmsd = &mv88w8618_audio_vmsd;
>>>>> -    dc->props = mv88w8618_audio_properties;
>>>>> -    /* Reason: pointer property "wm8750" */
>>>>> -    dc->user_creatable = false;
>>>>
>>>> Having a link property isn't it the same restriction?
>>>
>>> This task can found in
>>> https://wiki.qemu.org/Contribute/BiteSizedTasks#Device_models
>>>
>>> Convert qdev pointer properties (defined with DEFINE_PROP_PTR) to QOM
>>> links. Example: commit 873b4d3.
>>
>> I agree with the QOM conversion (the rest of this patch), what I'm
>> wondering is if declaring this device now user_creatable is correct. I
>> don't think we can set link property from command line, but maybe I'm
>> wrong because I never investigate/tried to do it.
>>
>> Maybe devices having link property are automatically marked as
>> user_creatable = false, then your change would be correct (except you
>> should explicit that in the commit message).
>>
>> I'll post another mail on the list to ask about that.
> 
> On https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg02531.html
> 
> Peter answered:
> 
>    I think whether a device with a link property is
>    user creatable might depend on what the property is
>    for and whether the device has a useful fallback for
>    "link not connected".
> 
> So if you look the realize function, there is no check on the linked object:
> 
>      static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>      {
>          mv88w8618_audio_state *s = MV88W8618_AUDIO(dev);
> 
>          wm8750_data_req_set(s->wm, mv88w8618_audio_callback, s);
>      }
> 
> Then the called function dereference the WM8750State:
> 
>      void wm8750_data_req_set(DeviceState *dev, data_req_cb *data_req,
>                               void *opaque)
>      {
>          WM8750State *s = WM8750(dev);
> 
>          s->data_req = data_req;
>          s->opaque = opaque;
>      }
> 
> So this patch is incorrect. You should either keep the
> 'dc->user_creatable = false' line, or add a check in the realize()
> function, as here:
> 
>      static void bcm2836_realize(DeviceState *dev, Error **errp)
>      {
>          Object *obj;
>          Error *err = NULL;
> 
>          obj = object_property_get_link(OBJECT(dev), "ram", &err);
>          if (obj == NULL) {
>              error_setg(errp, "%s: required ram link not found: %s",
>                         __func__, error_get_pretty(err));
>              return;
>          }
>          ...
> 

Sorry for the delay in response, I was away for the holiday weekend.
I saw the mail you discussed and reviewed the code, I will fix it in
the next version. Thank you! I really appreciate it.

Thanks,
Mao


> Regards,
> 
> Phil.
> 
>>
>> Regards,
>>
>> Phil.
>>
>>>
>>> Thanks,
>>> Mao
>>>
>>>>
>>>>>    }
>>>>>      static const TypeInfo mv88w8618_audio_info = {
>>>>>
>>>>
>>>
>>>
>

Patch

diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
index 3dafb41b0b..ac266f9253 100644
--- a/hw/arm/musicpal.c
+++ b/hw/arm/musicpal.c
@@ -1695,7 +1695,8 @@  static void musicpal_init(MachineState *machine)
     wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
     dev = qdev_create(NULL, "mv88w8618_audio");
     s = SYS_BUS_DEVICE(dev);
-    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
+    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
+                             TYPE_WM8750, NULL);
     qdev_init_nofail(dev);
     sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
     sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
index cf6ce6979b..baab4a3d53 100644
--- a/hw/audio/marvell_88w8618.c
+++ b/hw/audio/marvell_88w8618.c
@@ -15,6 +15,7 @@ 
 #include "hw/i2c/i2c.h"
 #include "hw/audio/wm8750.h"
 #include "audio/audio.h"
+#include "qapi/error.h"
 
 #define MP_AUDIO_SIZE           0x00001000
 
@@ -252,6 +253,11 @@  static void mv88w8618_audio_init(Object *obj)
     memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
                           "audio", MP_AUDIO_SIZE);
     sysbus_init_mmio(dev, &s->iomem);
+
+    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
+                             (Object **) &s->wm,
+                             qdev_prop_allow_set_link_before_realize,
+                             0, &error_abort);
 }
 
 static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
@@ -279,11 +285,6 @@  static const VMStateDescription mv88w8618_audio_vmsd = {
     }
 };
 
-static Property mv88w8618_audio_properties[] = {
-    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
-    {/* end of list */},
-};
-
 static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -291,9 +292,6 @@  static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
     dc->realize = mv88w8618_audio_realize;
     dc->reset = mv88w8618_audio_reset;
     dc->vmsd = &mv88w8618_audio_vmsd;
-    dc->props = mv88w8618_audio_properties;
-    /* Reason: pointer property "wm8750" */
-    dc->user_creatable = false;
 }
 
 static const TypeInfo mv88w8618_audio_info = {