Re: [Intel-gfx] [PATCH 13/18] drm/i915/guc: Relax CTB response timeout

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 26.05.2021 08:42, Matthew Brost wrote:
> From: Michal Wajdeczko <michal.wajdeczko@intel.com>
> 
> In upcoming patch we will allow more CTB requests to be sent in
> parallel to the GuC for processing, so we shouldn't assume any more
> that GuC will always reply without 10ms.
> 
> Use bigger value from CONFIG_DRM_I915_GUC_CTB_TIMEOUT instead.
> 
> v2: Add CONFIG_DRM_I915_GUC_CTB_TIMEOUT config option
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Reviewed-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/i915/Kconfig.profile      | 9 +++++++++
>  drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 5 ++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile
> index 39328567c200..68ac707755d2 100644
> --- a/drivers/gpu/drm/i915/Kconfig.profile
> +++ b/drivers/gpu/drm/i915/Kconfig.profile
> @@ -38,6 +38,15 @@ config DRM_I915_USERFAULT_AUTOSUSPEND
>  	  May be 0 to disable the extra delay and solely use the device level
>  	  runtime pm autosuspend delay tunable.
>  
> +config DRM_I915_GUC_CTB_TIMEOUT
> +	int "How long to wait for the GuC to make forward progress on CTBs (ms)"

maybe worth to provide here explicit allowed range:

	range 10 60000

and then we can skip runtime adjustment for minimum 10ms timeout

> +	default 1500 # milliseconds
> +	help
> +	  Configures the default timeout waiting for GuC the to make forward
> +	  progress on CTBs. e.g. Waiting for a response to requeset.

typo

> +
> +	  A minimum value of 10 ms is allowed.
> +
>  config DRM_I915_HEARTBEAT_INTERVAL
>  	int "Interval between heartbeat pulses (ms)"
>  	default 2500 # milliseconds
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index 916c2b80c841..5b0dece7a7cd 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -436,6 +436,7 @@ static int ct_write(struct intel_guc_ct *ct,
>   */
>  static int wait_for_ct_request_update(struct ct_request *req, u32 *status)
>  {
> +	long timeout;
>  	int err;
>  
>  	/*
> @@ -443,10 +444,12 @@ static int wait_for_ct_request_update(struct ct_request *req, u32 *status)
>  	 * up to that length of time, then switch to a slower sleep-wait loop.
>  	 * No GuC command should ever take longer than 10ms.
>  	 */
> +	timeout = max(10, CONFIG_DRM_I915_GUC_CTB_TIMEOUT);
> +
>  #define done INTEL_GUC_MSG_IS_RESPONSE(READ_ONCE(req->status))
>  	err = wait_for_us(done, 10);
>  	if (err)
> -		err = wait_for(done, 10);
> +		err = wait_for(done, timeout);
>  #undef done
>  
>  	if (unlikely(err))
> 
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