ACPI / LPSS: Only call pwm_add_table() for Bay Trail PWM if PMIC HRV is 2

The Point of View mobii wintab p800w Bay Trail tablet comes with a Crystal
Cove PMIC, yet uses the LPSS PWM for backlight control, rather then the
Crystal Cove's PWM, so we need to call pwm_add_table() to add a
pwm_backlight mapping for the LPSS pwm despite there being an INT33FD
ACPI device present.

On all Bay Trail devices the _HRV object of the INT33FD ACPI device
will normally return 2, to indicate the Bay Trail variant of the CRC
PMIC is present, except on this tablet where _HRV is 0xffff. I guess this
is a hack to make the windows Crystal Cove PWM driver not bind.

Out of the 44 DSTDs with an INT33FD device in there which I have (from
different model devices) only the pov mobii wintab p800w uses 0xffff for
the HRV.

The byt_pwm_setup code calls acpi_dev_present to check for the presence
of a INT33FD ACPI device which indicates that a CRC PMIC is present and
if the INT33FD ACPI device is present then byt_pwm_setup will not add
a pwm_backlight mapping for the LPSS pwm, so that the CRC PWM will get
used instead.

acpi_dev_present has a hrv parameter, this commit make us pass 2 instead
of -1, so that things still match on normal tablets, but on this special
case with its _HRV of 0xffff, the check will now fail so that the
pwm_backlight mapping for the LPSS pwm gets added fixing backlight
brightness control on this device.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/acpi_lpss.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

On Fri, 2018-04-13 at 14:54 +0200, Hans de Goede wrote:
> The Point of View mobii wintab p800w Bay Trail tablet comes with a
> Crystal
> Cove PMIC, yet uses the LPSS PWM for backlight control, rather then
> the
> Crystal Cove's PWM, so we need to call pwm_add_table() to add a
> pwm_backlight mapping for the LPSS pwm despite there being an INT33FD
> ACPI device present.
> 
> On all Bay Trail devices the _HRV object of the INT33FD ACPI device
> will normally return 2, to indicate the Bay Trail variant of the CRC
> PMIC is present, except on this tablet where _HRV is 0xffff. I guess
> this
> is a hack to make the windows Crystal Cove PWM driver not bind.
> 
> Out of the 44 DSTDs with an INT33FD device in there which I have (from
> different model devices) only the pov mobii wintab p800w uses 0xffff
> for
> the HRV.
> 
> The byt_pwm_setup code calls acpi_dev_present to check for the
> presence
> of a INT33FD ACPI device which indicates that a CRC PMIC is present
> and
> if the INT33FD ACPI device is present then byt_pwm_setup will not add
> a pwm_backlight mapping for the LPSS pwm, so that the CRC PWM will get
> used instead.
> 
> acpi_dev_present has a hrv parameter, this commit make us pass 2
> instead
> of -1, so that things still match on normal tablets, but on this
> special
> case with its _HRV of 0xffff, the check will now fail so that the
> pwm_backlight mapping for the LPSS pwm gets added fixing backlight
> brightness control on this device.
> 

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/acpi/acpi_lpss.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
> index c4ba9164e582..38a286975c31 100644
> --- a/drivers/acpi/acpi_lpss.c
> +++ b/drivers/acpi/acpi_lpss.c
> @@ -69,6 +69,10 @@ ACPI_MODULE_NAME("acpi_lpss");
>  #define LPSS_SAVE_CTX			BIT(4)
>  #define LPSS_NO_D3_DELAY		BIT(5)
>  
> +/* Crystal Cove PMIC shares same ACPI ID between different platforms
> */
> +#define BYT_CRC_HRV			2
> +#define CHT_CRC_HRV			3
> +
>  struct lpss_private_data;
>  
>  struct lpss_device_desc {
> @@ -162,7 +166,7 @@ static void byt_pwm_setup(struct lpss_private_data
> *pdata)
>  	if (!adev->pnp.unique_id || strcmp(adev->pnp.unique_id, "1"))
>  		return;
>  
> -	if (!acpi_dev_present("INT33FD", NULL, -1))
> +	if (!acpi_dev_present("INT33FD", NULL, BYT_CRC_HRV))
>  		pwm_add_table(byt_pwm_lookup,
> ARRAY_SIZE(byt_pwm_lookup));
>  }
>

On Friday, April 20, 2018 3:31:30 PM CEST Andy Shevchenko wrote:
> On Fri, 2018-04-13 at 14:54 +0200, Hans de Goede wrote:
> > The Point of View mobii wintab p800w Bay Trail tablet comes with a
> > Crystal
> > Cove PMIC, yet uses the LPSS PWM for backlight control, rather then
> > the
> > Crystal Cove's PWM, so we need to call pwm_add_table() to add a
> > pwm_backlight mapping for the LPSS pwm despite there being an INT33FD
> > ACPI device present.
> > 
> > On all Bay Trail devices the _HRV object of the INT33FD ACPI device
> > will normally return 2, to indicate the Bay Trail variant of the CRC
> > PMIC is present, except on this tablet where _HRV is 0xffff. I guess
> > this
> > is a hack to make the windows Crystal Cove PWM driver not bind.
> > 
> > Out of the 44 DSTDs with an INT33FD device in there which I have (from
> > different model devices) only the pov mobii wintab p800w uses 0xffff
> > for
> > the HRV.
> > 
> > The byt_pwm_setup code calls acpi_dev_present to check for the
> > presence
> > of a INT33FD ACPI device which indicates that a CRC PMIC is present
> > and
> > if the INT33FD ACPI device is present then byt_pwm_setup will not add
> > a pwm_backlight mapping for the LPSS pwm, so that the CRC PWM will get
> > used instead.
> > 
> > acpi_dev_present has a hrv parameter, this commit make us pass 2
> > instead
> > of -1, so that things still match on normal tablets, but on this
> > special
> > case with its _HRV of 0xffff, the check will now fail so that the
> > pwm_backlight mapping for the LPSS pwm gets added fixing backlight
> > brightness control on this device.
> > 
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Applied, thanks!

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