Re: [PATCH 14/18] drm/i915: Forcefully flush GuC log buffer on reset

["Goel, Akash" <akash.goel@intel.com>]

On 8/16/2016 4:57 PM, Tvrtko Ursulin wrote:
>
> On 15/08/16 15:49, akash.goel@intel.com wrote:
>> From: Sagar Arun Kamble <sagar.a.kamble@intel.com>
>>
>> Before capturing the GuC logs as a part of error state, there should be a
>> force log buffer flush action sent to GuC before proceeding with GPU
>> reset
>> and re-initializing GUC. There could be some data in the log buffer which
>> is yet to be captured and those logs would be particularly useful to
>> understand that why the GPU reset was initiated.
>>
>> v2:
>> - Avoid the wait via flush_work, to serialize against an ongoing log
>>    buffer flush, from the error state capture path. (Chris)
>> - Rebase.
>>
>> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
>> Signed-off-by: Akash Goel <akash.goel@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_gpu_error.c      |  2 ++
>>   drivers/gpu/drm/i915/i915_guc_submission.c | 30
>> ++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/i915/intel_guc.h           |  1 +
>>   3 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c
>> b/drivers/gpu/drm/i915/i915_gpu_error.c
>> index 94297aa..b73c671 100644
>> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
>> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
>> @@ -1301,6 +1301,8 @@ static void
>> i915_gem_capture_guc_log_buffer(struct drm_i915_private *dev_priv,
>>       if (!dev_priv->guc.log.vma || (i915.guc_log_level < 0))
>>           return;
>>
>> +    i915_guc_flush_logs(dev_priv, false);
>> +
>>       error->guc_log = i915_error_object_create(dev_priv,
>>                             dev_priv->guc.log.vma);
>>   }
>> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c
>> b/drivers/gpu/drm/i915/i915_guc_submission.c
>> index b8d6313..85df2f3 100644
>> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
>> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
>> @@ -185,6 +185,16 @@ static int
>> host2guc_logbuffer_flush_complete(struct intel_guc *guc)
>>       return host2guc_action(guc, data, 1);
>>   }
>>
>> +static int host2guc_force_logbuffer_flush(struct intel_guc *guc)
>> +{
>> +    u32 data[2];
>> +
>> +    data[0] = HOST2GUC_ACTION_FORCE_LOG_BUFFER_FLUSH;
>> +    data[1] = 0;
>> +
>> +    return host2guc_action(guc, data, 2);
>> +}
>> +
>>   /*
>>    * Initialise, update, or clear doorbell data shared with the GuC
>>    *
>> @@ -1536,6 +1546,26 @@ void i915_guc_capture_logs(struct
>> drm_i915_private *dev_priv)
>>       intel_runtime_pm_put(dev_priv);
>>   }
>>
>> +void i915_guc_flush_logs(struct drm_i915_private *dev_priv, bool
>> can_wait)
>> +{
>> +    if (!i915.enable_guc_submission || (i915.guc_log_level < 0))
>> +        return;
>> +
>> +    /* First disable the interrupts, will be renabled afterwards */
>> +    gen9_disable_guc_interrupts(dev_priv);
>> +
>> +    /* Before initiating the forceful flush, wait for any
>> pending/ongoing
>> +     * flush to complete otherwise forceful flush may not happen, but
>> wait
>> +     * can't be done for some paths like error state capture in which
>> case
>> +     * take a chance & directly attempt the forceful flush.
>> +     */
>> +    if (can_wait)
>> +        flush_work(&dev_priv->guc.log.flush_work);
>> +
>> +    /* Ask GuC to update the log buffer state */
>> +    host2guc_force_logbuffer_flush(&dev_priv->guc);
>
> Should you just call i915_guc_capture_logs from here? Error capture
> could also potentially benefit from it and you could remove it from the
> debugfs patch then.
>
Actually earlier it was done like that only, but now after adding the 
patch,
[PATCH 13/18] drm/i915: Augment i915 error state to include the dump of 
GuC log buffer,
Contents of GuC log buffer is anyways made part of the error state, so 
thought it may not be of any real use to capture the left over logs in 
the relay sub buffer also.
For the analysis purpose, GuC logs part of the error state dump would be 
good enough.

best regards
Akash
>> +}
>> +
>>   void i915_guc_unregister(struct drm_i915_private *dev_priv)
>>   {
>>       if (!i915.enable_guc_submission)
>> diff --git a/drivers/gpu/drm/i915/intel_guc.h
>> b/drivers/gpu/drm/i915/intel_guc.h
>> index 8598f38..d7eda42 100644
>> --- a/drivers/gpu/drm/i915/intel_guc.h
>> +++ b/drivers/gpu/drm/i915/intel_guc.h
>> @@ -182,6 +182,7 @@ int i915_guc_wq_check_space(struct
>> drm_i915_gem_request *rq);
>>   void i915_guc_submission_disable(struct drm_i915_private *dev_priv);
>>   void i915_guc_submission_fini(struct drm_i915_private *dev_priv);
>>   void i915_guc_capture_logs(struct drm_i915_private *dev_priv);
>> +void i915_guc_flush_logs(struct drm_i915_private *dev_priv, bool
>> can_wait);
>>   void i915_guc_register(struct drm_i915_private *dev_priv);
>>   void i915_guc_unregister(struct drm_i915_private *dev_priv);
>>
>>
>
> Regards,
>
> Tvrtko
>
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