linux-kernel - Re: [PATCH v2] mfd: intel_soc_pmic_crc: Use PWM_LOOKUP_WITH

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Date: Mon, 27 May 2024 13:49:16 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: Andy Shevchenko <andy@...nel.org>
Cc: Jani Nikula <jani.nikula@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mfd: intel_soc_pmic_crc: Use PWM_LOOKUP_WITH_MODULE()
 for the PWM lookup

Hi,

Ugh I send this to the wrong email address for Lee, so I'm going to resend it
with the right address, sorry about the spam.

Regards,

Hans


On 5/27/24 1:47 PM, Hans de Goede wrote:
> The primary use of the CRC PMIC's PWM is for LCD panel backlight
> control by the i915 driver.
> 
> Due to its complexity the probe() function of the i915 driver does not
> support -EPROBE_DEFER handling. So far the pwm-crc driver must be built
> into the kernel to ensure that the pwm_get() done by the i915 driver
> succeeds at once (rather then returning -EPROBE_DEFER).
> 
> But the PWM core can load the module from pwm_get() if a module-name is
> provided in the pwm_lookup associated with the consumer device.
> 
> Switch to using PWM_LOOKUP_WITH_MODULE() for the lookup added for
> the Intel integrated GPU, so that the PWM core can load the module from
> pwm_get() as needed allowing the pwm-crc driver to be safely built as
> module.
> 
> This has been successfully tested on an Asus T100TAM with pwm-crc
> build as a module.
> 
> Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11081
> Reviewed-by: Andy Shevchenko <andy@...nel.org>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
> Changes in v2:
> - Some small commit message tweaks
> - Add Andy's Reviewed-by
> ---
>  drivers/mfd/intel_soc_pmic_crc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/intel_soc_pmic_crc.c b/drivers/mfd/intel_soc_pmic_crc.c
> index 581f81cbaa24..876d017f74fe 100644
> --- a/drivers/mfd/intel_soc_pmic_crc.c
> +++ b/drivers/mfd/intel_soc_pmic_crc.c
> @@ -137,7 +137,9 @@ static const struct regmap_irq_chip crystal_cove_irq_chip = {
>  
>  /* PWM consumed by the Intel GFX */
>  static struct pwm_lookup crc_pwm_lookup[] = {
> -	PWM_LOOKUP("crystal_cove_pwm", 0, "0000:00:02.0", "pwm_pmic_backlight", 0, PWM_POLARITY_NORMAL),
> +	PWM_LOOKUP_WITH_MODULE("crystal_cove_pwm", 0, "0000:00:02.0",
> +			       "pwm_pmic_backlight", 0, PWM_POLARITY_NORMAL,
> +			       "pwm-crc"),
>  };
>  
>  struct crystal_cove_config {