Re: [PATCH 2/5] drm/xe/reg_sr: Write all whitelist slots

[Matt Roper <matthew.d.roper@intel.com>]

On Thu, Dec 05, 2024 at 10:22:37AM -0800, Lucas De Marchi wrote:
> Currently if there's 1 whitelisted register in the engine, on slot is
> written with that register and all the others are written to a sane
> value. For the free slots, there's no reason to change the behavior
> if there are 0, 1 or slots occupied. If the default value from HW is not
> trusted, all values should be written to.
> 
> Also, later on all values are passed to GuC via ADS to be restored on
> engine reset, so make sure they are also written to when probing the
> device.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

I don't think it really matters too much one way or another.  There's no
enabled/disabled setting for the force_to_nonpriv registers so we
replace the hardware-defined "garbage" value with our own "garbage"
value for the ununsed entries, but what really matters are the ones that
are set.

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

> ---
>  drivers/gpu/drm/xe/xe_reg_sr.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_reg_sr.c b/drivers/gpu/drm/xe/xe_reg_sr.c
> index c13123008e903..f982c1cdb369c 100644
> --- a/drivers/gpu/drm/xe/xe_reg_sr.c
> +++ b/drivers/gpu/drm/xe/xe_reg_sr.c
> @@ -204,9 +204,6 @@ void xe_reg_sr_apply_whitelist(struct xe_hw_engine *hwe)
>  	unsigned int slot = 0;
>  	unsigned int fw_ref;
>  
> -	if (xa_empty(&sr->xa))
> -		return;
> -
>  	drm_dbg(&xe->drm, "Whitelisting %s registers\n", sr->name);
>  
>  	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> -- 
> 2.47.0
> 

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