[PATCH v6 4/4] drm/i915/display: Increase number of fast wake precharge pulses

[Ville Syrjälä]

On Wed, Mar 13, 2024 at 03:32:21PM +0200, Jouni Högander wrote:
> Increasing number of fast wake sync pulses seem to fix problems with
> certain PSR panels. This should be ok for other panels as well as the eDP
> specification allows 10...16 precharge pulses and we are still within that
> range.
> 
> v2: add comment explaining pulse count is increased
> 
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9739
> Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_aux.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> index 7e69be100d90..3264026454b2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> @@ -145,7 +145,12 @@ static int intel_dp_aux_sync_len(void)
>  
>  int intel_dp_aux_fw_sync_len(void)
>  {
> -	int precharge = 10; /* 10-16 */
> +	/*
> +	 * We faced some glitches on MTL with one PSR2 panel when using HW
> +	 * default 18. Using 20 is fixing these problems with the panel. It is
> +	 * still within range mentioned in eDP specification.
> +	 */

"MTL with one PSR2 panel" is super vague. Please mention the
actual machine model here.

With that 
Acked-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> +	int precharge = 12; /* 10-16 */
>  	int preamble = 8;
>  
>  	return precharge + preamble;
> -- 
> 2.34.1

-- 
Ville Syrjälä
Intel