[PATCH v3] drm/i915/display: Don't update DBUF_TRACKER_STATE_SERVICE

[Matt Roper]

On Thu, Jan 09, 2025 at 01:32:10AM +0530, Ravi Kumar Vodapalli wrote:
> The bspec only asks the driver to reprogram the DBUF_CTL's
> DBUF_TRACKER_STATE_SERVICE field to 0x8 on DG2 and platforms with
> display version 12. All other platforms should avoid reprogramming
> this register at driver init.
> 
> Although we've been accidentally reprogramming DBUF_CTL on platforms
> where the spec does not ask us to, that mistake has been harmless so
> far because the value being programmed by the driver happened to
> match the hardware's default settings.
> 
> So, update DBUF_TRACKER_STATE_SERVICE field to 0x8 only for
> 1. display version 12
> 2. DG2.
> Other platforms unless stated should use their default value.
> 
> Bspec: 49213
> Signed-off-by: Ravi Kumar Vodapalli <ravi.kumar.vodapalli at intel.com>

I just noticed that the patch subject isn't quite right (it implies that
we aren't updating that field on _any_ platforms), but I can tweak that
while applying the patch; no need to re-send.

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

And since the CI results on the previous version were clean (aside from
one false positive on a DG1 GEM test) and the only changes in this
version are to the commit message, applied to drm-intel-next.  Thanks
for the patch.


Matt

> ---
>  drivers/gpu/drm/i915/display/intel_display_power.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 34465d56def0..9c20459053fe 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -1126,9 +1126,6 @@ static void gen12_dbuf_slices_config(struct intel_display *display)
>  {
>  	enum dbuf_slice slice;
>  
> -	if (display->platform.alderlake_p)
> -		return;
> -
>  	for_each_dbuf_slice(display, slice)
>  		intel_de_rmw(display, DBUF_CTL_S(slice),
>  			     DBUF_TRACKER_STATE_SERVICE_MASK,
> @@ -1681,7 +1678,7 @@ static void icl_display_core_init(struct intel_display *display,
>  	/* 4. Enable CDCLK. */
>  	intel_cdclk_init_hw(display);
>  
> -	if (DISPLAY_VER(display) >= 12)
> +	if (DISPLAY_VER(display) == 12 || display->platform.dg2)
>  		gen12_dbuf_slices_config(display);
>  
>  	/* 5. Enable DBUF. */
> -- 
> 2.25.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation