Re: [PATCH 1/6] drm/i915/pcode: drop fast wait from snb_pcode_write_timeout()

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Thu, Jun 05, 2025 at 01:29:33PM +0300, Jani Nikula wrote:
> Only use the ms granularity wait in snb_pcode_write_timeout(), primarily
> to better align with the xe driver, which also only has the millisecond
> wait.
> 
> Use an arbitrary 250 us fast wait before the specified ms wait, and have
> snb_pcode_write() default to 1 ms.
> 
> This means snb_pcode_write() and snb_pcode_write_timeout() will always
> be sleeping functions. There should not be any atomic users for pcode
> writes though, and any display code using pcode via xe has already been
> non-atomic. The uncore wait will do a might_sleep() annotation that
> should catch any problems.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_cdclk.c              | 5 ++---
>  drivers/gpu/drm/i915/display/intel_display_power_well.c | 3 +--
>  drivers/gpu/drm/i915/intel_pcode.c                      | 5 ++---
>  drivers/gpu/drm/i915/intel_pcode.h                      | 5 ++---
>  drivers/gpu/drm/xe/compat-i915-headers/intel_pcode.h    | 6 ++----
>  5 files changed, 9 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index f0c673e40ce5..7ad506da7d3d 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -2147,7 +2147,7 @@ static void bxt_set_cdclk(struct intel_display *display,
>  		 */
>  		ret = snb_pcode_write_timeout(&dev_priv->uncore,
>  					      HSW_PCODE_DE_WRITE_FREQ_REQ,
> -					      0x80000000, 150, 2);
> +					      0x80000000, 2);
>  
>  	if (ret) {
>  		drm_err(display->drm,
> @@ -2187,8 +2187,7 @@ static void bxt_set_cdclk(struct intel_display *display,
>  		 */
>  		ret = snb_pcode_write_timeout(&dev_priv->uncore,
>  					      HSW_PCODE_DE_WRITE_FREQ_REQ,
> -					      cdclk_config->voltage_level,
> -					      150, 2);
> +					      cdclk_config->voltage_level, 2);
>  	}
>  	if (ret) {
>  		drm_err(display->drm,
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.c b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> index 02e3c22be21e..e60f60ddbff7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power_well.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> @@ -485,8 +485,7 @@ static void icl_tc_cold_exit(struct intel_display *display)
>  	int ret, tries = 0;
>  
>  	while (1) {
> -		ret = snb_pcode_write_timeout(&i915->uncore, ICL_PCODE_EXIT_TCCOLD, 0,
> -					      250, 1);
> +		ret = snb_pcode_write(&i915->uncore, ICL_PCODE_EXIT_TCCOLD, 0);
>  		if (ret != -EAGAIN || ++tries == 3)
>  			break;
>  		msleep(1);
> diff --git a/drivers/gpu/drm/i915/intel_pcode.c b/drivers/gpu/drm/i915/intel_pcode.c
> index 3db2ba439bb5..b7e9b4ee1425 100644
> --- a/drivers/gpu/drm/i915/intel_pcode.c
> +++ b/drivers/gpu/drm/i915/intel_pcode.c
> @@ -110,13 +110,12 @@ int snb_pcode_read(struct intel_uncore *uncore, u32 mbox, u32 *val, u32 *val1)
>  }
>  
>  int snb_pcode_write_timeout(struct intel_uncore *uncore, u32 mbox, u32 val,
> -			    int fast_timeout_us, int slow_timeout_ms)
> +			    int timeout_ms)
>  {
>  	int err;
>  
>  	mutex_lock(&uncore->i915->sb_lock);
> -	err = __snb_pcode_rw(uncore, mbox, &val, NULL,
> -			     fast_timeout_us, slow_timeout_ms, false);
> +	err = __snb_pcode_rw(uncore, mbox, &val, NULL, 250, timeout_ms, false);
>  	mutex_unlock(&uncore->i915->sb_lock);
>  
>  	if (err) {
> diff --git a/drivers/gpu/drm/i915/intel_pcode.h b/drivers/gpu/drm/i915/intel_pcode.h
> index 8d2198e29422..401ce27f72d4 100644
> --- a/drivers/gpu/drm/i915/intel_pcode.h
> +++ b/drivers/gpu/drm/i915/intel_pcode.h
> @@ -11,10 +11,9 @@
>  struct intel_uncore;
>  
>  int snb_pcode_read(struct intel_uncore *uncore, u32 mbox, u32 *val, u32 *val1);
> -int snb_pcode_write_timeout(struct intel_uncore *uncore, u32 mbox, u32 val,
> -			    int fast_timeout_us, int slow_timeout_ms);
> +int snb_pcode_write_timeout(struct intel_uncore *uncore, u32 mbox, u32 val, int timeout_ms);
>  #define snb_pcode_write(uncore, mbox, val) \
> -	snb_pcode_write_timeout(uncore, mbox, val, 500, 0)
> +	snb_pcode_write_timeout((uncore), (mbox), (val), 1)
>  
>  int skl_pcode_request(struct intel_uncore *uncore, u32 mbox, u32 request,
>  		      u32 reply_mask, u32 reply, int timeout_base_ms);
> diff --git a/drivers/gpu/drm/xe/compat-i915-headers/intel_pcode.h b/drivers/gpu/drm/xe/compat-i915-headers/intel_pcode.h
> index a473aa6697d0..32da708680c2 100644
> --- a/drivers/gpu/drm/xe/compat-i915-headers/intel_pcode.h
> +++ b/drivers/gpu/drm/xe/compat-i915-headers/intel_pcode.h
> @@ -10,11 +10,9 @@
>  #include "xe_pcode.h"
>  
>  static inline int
> -snb_pcode_write_timeout(struct intel_uncore *uncore, u32 mbox, u32 val,
> -			int fast_timeout_us, int slow_timeout_ms)
> +snb_pcode_write_timeout(struct intel_uncore *uncore, u32 mbox, u32 val, int timeout_ms)
>  {
> -	return xe_pcode_write_timeout(__compat_uncore_to_tile(uncore), mbox, val,
> -				      slow_timeout_ms ?: 1);
> +	return xe_pcode_write_timeout(__compat_uncore_to_tile(uncore), mbox, val, timeout_ms);
>  }
>  
>  static inline int
> -- 
> 2.39.5
>