[PATCH v2] drm/i915/display: Implement wa_14024400148

[Kahola, Mika]

> -----Original Message-----
> From: Garg, Nemesa <nemesa.garg at intel.com>
> Sent: Wednesday, 16 April 2025 18.21
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org; Kahola, Mika
> <mika.kahola at intel.com>
> Cc: Garg, Nemesa <nemesa.garg at intel.com>
> Subject: [PATCH v2] drm/i915/display: Implement wa_14024400148
> 
> Workaround recommend use polling method
> for pm_demand to finish as to avoid timeout.
> 
> v2: Add polling method within pmdemand_wait.
>     Update error message[Jani]
> 
> Signed-off-by: Nemesa Garg <nemesa.garg at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_pmdemand.c | 31 ++++++++++++++++---
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_pmdemand.c
> b/drivers/gpu/drm/i915/display/intel_pmdemand.c
> index d22b5469672d..1253376c7654 100644
> --- a/drivers/gpu/drm/i915/display/intel_pmdemand.c
> +++ b/drivers/gpu/drm/i915/display/intel_pmdemand.c
> @@ -478,13 +478,34 @@ static bool intel_pmdemand_req_complete(struct
> intel_display *display)
>  		 XELPDP_PMDEMAND_REQ_ENABLE);
>  }
> 
> -static void intel_pmdemand_wait(struct intel_display *display)
> +static void intel_pmdemand_poll(struct intel_display *display)
>  {
> -	if (!wait_event_timeout(display->pmdemand.waitqueue,
> -				intel_pmdemand_req_complete(display),
> -				msecs_to_jiffies_timeout(10)))
> +	const unsigned int timeout_ms = 10;
> +	u32 status;
> +	int ret;
> +
> +	ret = intel_de_wait_custom(display,
> XELPDP_INITIATE_PMDEMAND_REQUEST(1),
> +				   XELPDP_PMDEMAND_REQ_ENABLE, 0,
> +				   50, timeout_ms, &status);
> +
> +	if (ret == -ETIMEDOUT)
>  		drm_err(display->drm,
> -			"timed out waiting for Punit PM Demand Response\n");
> +			"timed out waiting for Punit PM Demand Response
> within %ums (status 0x%08x)\n",
> +			timeout_ms, status);
> +}
> +
> +static void intel_pmdemand_wait(struct intel_display *display) {
> +	/* Wa_14024400148 For lnl use polling method */
> +	if (DISPLAY_VER(display) == 20) {
> +		intel_pmdemand_poll(display);
> +	} else {

Maybe this else branch could be written as its own function as with if branch. Anyway, this might be a topic for follow up patch.

Reviewed-by: Mika Kahola <mika.kahola at intel.com>

> +		if (!wait_event_timeout(display->pmdemand.waitqueue,
> +
> 	intel_pmdemand_req_complete(display),
> +					msecs_to_jiffies_timeout(10)))
> +			drm_err(display->drm,
> +				"timed out waiting for Punit PM Demand
> Response\n");
> +	}
>  }
> 
>  /* Required to be programmed during Display Init Sequences. */
> --
> 2.25.1