[PATCH v3 1/3] drm/i915/pxp/mtl: Update pxp-firmware response timeout

[Teres Alexis, Alan Previn]

On Tue, 2023-08-15 at 13:29 -0700, Teres Alexis, Alan Previn wrote:
> Update the max GSC-fw response time to match updated internal
> fw specs. Because this response time is an SLA on the firmware,
> not inclusive of i915->GuC->HW handoff latency, when submitting
> requests to the GSC fw via intel_gsc_uc_heci_cmd_submit_nonpriv,
> start the count after the request hits the GSC command streamer.
> 
> Signed-off-by: Alan Previn <alan.previn.teres.alexis at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/uc/intel_gsc_uc_heci_cmd_submit.c | 3 +++
>  drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.h                | 6 +++---
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_gsc_uc_heci_cmd_submit.c b/drivers/gpu/drm/i915/gt/uc/intel_gsc_uc_heci_cmd_submit.c
> index 89ed5ee9cded..ae45855594ac 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_gsc_uc_heci_cmd_submit.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_gsc_uc_heci_cmd_submit.c
> @@ -186,6 +186,9 @@ intel_gsc_uc_heci_cmd_submit_nonpriv(struct intel_gsc_uc *gsc,
>  	i915_request_add(rq);
>  
>  	if (!err) {
> +		if (wait_for(i915_request_started(rq), 200))
> +			drm_dbg(&gsc_uc_to_gt(gsc)->i915->drm,
> +				"Delay in gsc-heci-non-priv submission to gsccs-hw");
alan: offline discussion with Daniele, Daniele provided the following review comments:
We should add this wait-check for both priv and non-priv but we should increase the
timeout to be more than the guaranteed fw response time of 1 other message (since we
have a total of 2 contexts that could be sending messages concurrently at any time
including this one)... so maybe timeout of the new GSC_REPLY_LATENCY_MS + 150.
More importantly, he highlighted the fact that we should wait for the request-started
AND ensure there as no error in request status.

[snip]