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

[John Harrison <john.c.harrison@intel.com>]

On 12/5/2024 10:22, 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
The values are not passed to GuC, only the register addresses. GuC does 
a read prior to reset and a write post reset of the registers to 
preserve their value at the point of reset. It does not blanket restore 
a fixed value set by the KMD at start of day.

John.

> engine reset, so make sure they are also written to when probing the
> device.
>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@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);