[PATCH v3 3/8] drm/i915/dp: Initialize the source OUI write timestamp always

[Ville Syrjälä]

On Wed, Oct 16, 2024 at 04:24:00PM +0300, Imre Deak wrote:
> If the source OUI DPCD register value matches the expected Intel OUI
> value, the write timestamp doesn't get updated leaving it at the 0
> initial value if the OUI wasn't written before. This can lead to an
> incorrect wait duration in intel_dp_wait_source_oui(), since jiffies is
> not inited to 0 in general (on a 32 bit system INITIAL_JIFFIES is set to
> 5 minutes ahead of wrap-around). Fix this by intializing the write
> timestamp in the above case as well.
> 
> Signed-off-by: Imre Deak <imre.deak at intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 3da06d25bc4ef..0b9981f7f1a68 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3414,8 +3414,11 @@ intel_edp_init_source_oui(struct intel_dp *intel_dp, bool careful)
>  		if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf, sizeof(buf)) < 0)
>  			drm_err(&i915->drm, "Failed to read source OUI\n");
>  
> -		if (memcmp(oui, buf, sizeof(oui)) == 0)
> +		if (memcmp(oui, buf, sizeof(oui)) == 0) {
> +			/* Assume the OUI was written now. */
> +			intel_dp->last_oui_write = jiffies;
>  			return;
> +		}
>  	}
>  
>  	if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui, sizeof(oui)) < 0)
> -- 
> 2.44.2

-- 
Ville Syrjälä
Intel