[PATCH 3/3] drm/i915/dp: Include the time taken by AUX Tx for timeout

[Kandpal, Suraj]

> -----Original Message-----
> From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of Arun R
> Murthy
> Sent: Thursday, September 12, 2024 10:36 AM
> To: intel-xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> Cc: Murthy, Arun R <arun.r.murthy at intel.com>; Srikanth V, NagaVenkata
> <nagavenkata.srikanth.v at intel.com>
> Subject: [PATCH 3/3] drm/i915/dp: Include the time taken by AUX Tx for
> timeout
> 
> As per DP spec the timeout for LANE_CHANNEL_EQ_DONE is 400ms. But this

Adding where in DP spec example dp2.1 section x.x is a good idea

> timeout value is exclusively for the Aux RD Interval and excludes the time
> consumed for the AUX Tx (i.e reading/writing FFE presets). Add another
> 50ms for these AUX Tx to the 400ms timeout.

Is this something we came up with by trial and error or is this also a part of spec

Regards,
Suraj Kandpal
> 
> Signed-off-by: Srikanth V NagaVenkata <nagavenkata.srikanth.v at intel.com>
> Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_link_training.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index ca179bed46ad..b6573934c6dd 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -1414,7 +1414,7 @@ intel_dp_128b132b_lane_eq(struct intel_dp
> *intel_dp,
>  	}
> 
>  	/* Time budget for the LANEx_EQ_DONE Sequence */
> -	deadline = jiffies + msecs_to_jiffies_timeout(400);
> +	deadline = jiffies + msecs_to_jiffies_timeout(450);
> 
>  	for (try = 0; try < max_tries; try++) {
>  		fsleep(delay_us);
> --
> 2.25.1