[v2,2/2] mmc: sdhci-of-aspeed: add inversion signal presence
diff mbox series

Message ID 20191114125435.27756-3-i.mikhaylov@yadro.com
State New
Headers show
Series
  • add inversion signal presence support
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Commit Message

Ivan Mikhaylov Nov. 14, 2019, 12:54 p.m. UTC
Change the default .get_cd callback. Add inverted signal card detection
check.

Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>

Comments

Adrian Hunter Nov. 14, 2019, 1:10 p.m. UTC | #1
On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
> Change the default .get_cd callback. Add inverted signal card detection
> check.
> 
> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> 
> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-aspeed.c
> index 8962f6664381..186559ee8fcc 100644
> --- a/drivers/mmc/host/sdhci-of-aspeed.c
> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
> @@ -143,6 +143,19 @@ static inline int aspeed_sdhci_calculate_slot(struct aspeed_sdhci *dev,
>  	return (delta / 0x100) - 1;
>  }
>  
> +static int aspeed_get_cd(struct mmc_host *mmc)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +
> +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
> +			 & SDHCI_CARD_PRESENT);
> +
> +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> +		present = !present;

Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
->readl() callback

> +
> +	return present;
> +}
> +
>  static int aspeed_sdhci_probe(struct platform_device *pdev)
>  {
>  	struct sdhci_pltfm_host *pltfm_host;
> @@ -183,6 +196,10 @@ static int aspeed_sdhci_probe(struct platform_device *pdev)
>  		goto err_pltfm_free;
>  	}
>  
> +	host->mmc_host_ops.get_cd = aspeed_get_cd;
> +	if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
> +		dev_info(&pdev->dev, "aspeed: sdhci: presence signal inversion enabled\n");

Is this print really needed?

> +
>  	ret = mmc_of_parse(host->mmc);
>  	if (ret)
>  		goto err_sdhci_add;
>
Ivan Mikhaylov Nov. 14, 2019, 5:19 p.m. UTC | #2
On Thu, 2019-11-14 at 15:10 +0200, Adrian Hunter wrote:
> On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
> > Change the default .get_cd callback. Add inverted signal card detection
> > check.
> > 
> > Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> > 
> > diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-
> > aspeed.c
> > index 8962f6664381..186559ee8fcc 100644
> > --- a/drivers/mmc/host/sdhci-of-aspeed.c
> > +++ b/drivers/mmc/host/sdhci-of-aspeed.c
> > @@ -143,6 +143,19 @@ static inline int aspeed_sdhci_calculate_slot(struct
> > aspeed_sdhci *dev,
> >  	return (delta / 0x100) - 1;
> >  }
> >  
> > +static int aspeed_get_cd(struct mmc_host *mmc)
> > +{
> > +	struct sdhci_host *host = mmc_priv(mmc);
> > +
> > +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
> > +			 & SDHCI_CARD_PRESENT);
> > +
> > +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> > +		present = !present;
> 
> Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
> ->readl() callback
> 

Sorry, don't quite understand what you're saying. You want to instantiate
'.read_l' callback instead of '.get_cd' in sdhci_ops and substitute the real
value?

res = readl(base, reg);
if (reg == SDHCI_PRESENT_STATE)
	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
		return !res;
return res;

Something like this?

>  
> > +	host->mmc_host_ops.get_cd = aspeed_get_cd;
> > +	if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
> > +		dev_info(&pdev->dev, "aspeed: sdhci: presence signal inversion
> > enabled\n");
> 
> Is this print really needed?
> 
I can remove it if you think it's redundant.

Thanks.
Adrian Hunter Nov. 15, 2019, 7:20 a.m. UTC | #3
On 14/11/19 7:19 PM, Ivan Mikhaylov wrote:
> On Thu, 2019-11-14 at 15:10 +0200, Adrian Hunter wrote:
>> On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
>>> Change the default .get_cd callback. Add inverted signal card detection
>>> check.
>>>
>>> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
>>>
>>> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-
>>> aspeed.c
>>> index 8962f6664381..186559ee8fcc 100644
>>> --- a/drivers/mmc/host/sdhci-of-aspeed.c
>>> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
>>> @@ -143,6 +143,19 @@ static inline int aspeed_sdhci_calculate_slot(struct
>>> aspeed_sdhci *dev,
>>>  	return (delta / 0x100) - 1;
>>>  }
>>>  
>>> +static int aspeed_get_cd(struct mmc_host *mmc)
>>> +{
>>> +	struct sdhci_host *host = mmc_priv(mmc);
>>> +
>>> +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
>>> +			 & SDHCI_CARD_PRESENT);
>>> +
>>> +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
>>> +		present = !present;
>>
>> Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
>> ->readl() callback
>>
> 
> Sorry, don't quite understand what you're saying. You want to instantiate
> '.read_l' callback instead of '.get_cd' in sdhci_ops and substitute the real
> value?
> 
> res = readl(base, reg);
> if (reg == SDHCI_PRESENT_STATE)
> 	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> 		return !res;

Presumably just flip the SDHCI_CARD_PRESENT bit i.e.

		return res ^ SDHCI_CARD_PRESENT;

> return res;
> 
> Something like this?

Yes

> 
>>  
>>> +	host->mmc_host_ops.get_cd = aspeed_get_cd;
>>> +	if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
>>> +		dev_info(&pdev->dev, "aspeed: sdhci: presence signal inversion
>>> enabled\n");
>>
>> Is this print really needed?
>>
> I can remove it if you think it's redundant.
> 
> Thanks.
> 
>
Ivan Mikhaylov Nov. 15, 2019, 12:56 p.m. UTC | #4
On Fri, 2019-11-15 at 09:20 +0200, Adrian Hunter wrote:
> On 14/11/19 7:19 PM, Ivan Mikhaylov wrote:
> > On Thu, 2019-11-14 at 15:10 +0200, Adrian Hunter wrote:
> > On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
> > > > Change the default .get_cd callback. Add inverted signal card detection
> > > > check.
> > > > 
> > > > Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> > > > 
> > > > diff --git a/drivers/mmc/host/sdhci-of-aspeed.c
> > > > b/drivers/mmc/host/sdhci-of-
> > > > aspeed.c
> > > > index 8962f6664381..186559ee8fcc 100644
> > > > --- a/drivers/mmc/host/sdhci-of-aspeed.c
> > > > +++ b/drivers/mmc/host/sdhci-of-aspeed.c
> > > > @@ -143,6 +143,19 @@ static inline int
> > > > aspeed_sdhci_calculate_slot(struct
> > > > aspeed_sdhci *dev,
> > > >  	return (delta / 0x100) - 1;
> > > >  }
> > > >  
> > > > +static int aspeed_get_cd(struct mmc_host *mmc)
> > > > +{
> > > > +	struct sdhci_host *host = mmc_priv(mmc);
> > > > +
> > > > +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
> > > > +			 & SDHCI_CARD_PRESENT);
> > > > +
> > > > +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> > > > +		present = !present;
> > > 
> > > Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
> > > ->readl() callback
> 
> 
> > Sorry, don't quite understand what you're saying. You want to instantiate
> > '.read_l' callback instead of '.get_cd' in sdhci_ops and substitute the real
> > value?
> > 
> > res = readl(base, reg);
> > if (reg == SDHCI_PRESENT_STATE)
> > 	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> > 		return !res;
> 
> Presumably just flip the SDHCI_CARD_PRESENT bit i.e.
> 
> 		return res ^ SDHCI_CARD_PRESENT;
> 
> > return res;
> > 
> > Something like this?
> 
> Yes
> 

Don't you think it will bring a little overhead on any sdhci_readl plus
sdhci_readl will not get the real value in case of inverted signal which seems
is not right from communication fairness between hw and sw? I took that approach
with .get_cd from variety of drivers in host/mmc but if you think it will be
better and safer with .read_l - I'll do that way. 

Sorry for the link in subject, didn't notice that I put it in previous message
somehow.

Thanks.
Adrian Hunter Nov. 15, 2019, 1:17 p.m. UTC | #5
On 15/11/19 2:56 PM, Ivan Mikhaylov wrote:
> On Fri, 2019-11-15 at 09:20 +0200, Adrian Hunter wrote:
>> On 14/11/19 7:19 PM, Ivan Mikhaylov wrote:
>>> On Thu, 2019-11-14 at 15:10 +0200, Adrian Hunter wrote:
>>> On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
>>>>> Change the default .get_cd callback. Add inverted signal card detection
>>>>> check.
>>>>>
>>>>> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
>>>>>
>>>>> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c
>>>>> b/drivers/mmc/host/sdhci-of-
>>>>> aspeed.c
>>>>> index 8962f6664381..186559ee8fcc 100644
>>>>> --- a/drivers/mmc/host/sdhci-of-aspeed.c
>>>>> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
>>>>> @@ -143,6 +143,19 @@ static inline int
>>>>> aspeed_sdhci_calculate_slot(struct
>>>>> aspeed_sdhci *dev,
>>>>>  	return (delta / 0x100) - 1;
>>>>>  }
>>>>>  
>>>>> +static int aspeed_get_cd(struct mmc_host *mmc)
>>>>> +{
>>>>> +	struct sdhci_host *host = mmc_priv(mmc);
>>>>> +
>>>>> +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
>>>>> +			 & SDHCI_CARD_PRESENT);
>>>>> +
>>>>> +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
>>>>> +		present = !present;
>>>>
>>>> Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
>>>> ->readl() callback
>>
>>
>>> Sorry, don't quite understand what you're saying. You want to instantiate
>>> '.read_l' callback instead of '.get_cd' in sdhci_ops and substitute the real
>>> value?
>>>
>>> res = readl(base, reg);
>>> if (reg == SDHCI_PRESENT_STATE)
>>> 	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
>>> 		return !res;
>>
>> Presumably just flip the SDHCI_CARD_PRESENT bit i.e.
>>
>> 		return res ^ SDHCI_CARD_PRESENT;
>>
>>> return res;
>>>
>>> Something like this?
>>
>> Yes
>>
> 
> Don't you think it will bring a little overhead on any sdhci_readl plus

Register accesses are usually slow (~1us) compared with logic.  Of course,
I/O requests are even slower >100ms so it is unlikely that the overhead is
significant.

> sdhci_readl will not get the real value in case of inverted signal which seems
> is not right from communication fairness between hw and sw? I took that approach

One of the purposes of the accessors is to smooth over the difference
between the SDHCI standard and actual hardware.  Given that
SDHCI_PRESENT_STATE is also used in sdhci_set_card_detection() and
sdhci_irq(), it is surprising that changing only ->get_cd() works correctly.

> with .get_cd from variety of drivers in host/mmc but if you think it will be
> better and safer with .read_l - I'll do that way. 
> 
> Sorry for the link in subject, didn't notice that I put it in previous message
> somehow.
> 
> Thanks.
> 
>

Patch
diff mbox series

diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-aspeed.c
index 8962f6664381..186559ee8fcc 100644
--- a/drivers/mmc/host/sdhci-of-aspeed.c
+++ b/drivers/mmc/host/sdhci-of-aspeed.c
@@ -143,6 +143,19 @@  static inline int aspeed_sdhci_calculate_slot(struct aspeed_sdhci *dev,
 	return (delta / 0x100) - 1;
 }
 
+static int aspeed_get_cd(struct mmc_host *mmc)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+
+	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
+			 & SDHCI_CARD_PRESENT);
+
+	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
+		present = !present;
+
+	return present;
+}
+
 static int aspeed_sdhci_probe(struct platform_device *pdev)
 {
 	struct sdhci_pltfm_host *pltfm_host;
@@ -183,6 +196,10 @@  static int aspeed_sdhci_probe(struct platform_device *pdev)
 		goto err_pltfm_free;
 	}
 
+	host->mmc_host_ops.get_cd = aspeed_get_cd;
+	if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
+		dev_info(&pdev->dev, "aspeed: sdhci: presence signal inversion enabled\n");
+
 	ret = mmc_of_parse(host->mmc);
 	if (ret)
 		goto err_sdhci_add;