[Intel-gfx] [PATCH 4/8] drm/i915/guc: Disable critical logging in GuC by default from GuC v9

[Srivatsa, Anusha]

>-----Original Message-----
>From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of
>Kamble, Sagar A
>Sent: Monday, August 14, 2017 3:45 AM
>To: Chris Wilson <chris at chris-wilson.co.uk>; intel-gfx at lists.freedesktop.org
>Subject: Re: [Intel-gfx] [PATCH 4/8] drm/i915/guc: Disable critical logging in GuC
>by default from GuC v9
>
>
>
>-----Original Message-----
>From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
>Sent: Wednesday, August 9, 2017 4:20 PM
>To: Kamble, Sagar A <sagar.a.kamble at intel.com>; intel-
>gfx at lists.freedesktop.org
>Subject: Re: [Intel-gfx] [PATCH 4/8] drm/i915/guc: Disable critical logging in GuC
>by default from GuC v9
>
>Quoting Sagar Arun Kamble (2017-08-09 11:23:48)
>> From GuC v9 firmware (for KBL v9.39+), separate control is added to
>> enable critical logging in GuC to enable capturing minimal important
>> logs in production systems.
>> i915.guc_log_level controls the verbosity and logging in GuC for logs
>> other than critical logs. By default, logging in GuC is disabled
>> through i915.guc_log_level.
>> This patch introduces new kernel param i915.enable_guc_critical_logging.
>> For Linux release builds, if needed critical GuC logs can be enabled
>> separately through this parameter. GuC log snapshot captured in error
>> state will have these minimal critical events logged.
>> Default value for this parameter is currently set to false.
>> This patch updates the initialization parameter sent during GuC load
>> to disable critical logging unless i915.guc_log_level is set to enable
>> logging and ensures it is enabled/disabling while enabling/disabling
>> through debugfs based on i915.enable_guc_critical_logging.
>>
>> Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
>> Cc: Spotswood John A <john.a.spotswood at intel.com>
>> Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
>> Signed-off-by: Jeff McGee <jeff.mcgee at intel.com>
>> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble at intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_params.c      |  5 +++++
>>  drivers/gpu/drm/i915/i915_params.h      |  3 ++-
>>  drivers/gpu/drm/i915/intel_guc_fwif.h   | 14 +++++++++++++-
>>  drivers/gpu/drm/i915/intel_guc_loader.c | 21 ++++++++++++++++++++-
>>  drivers/gpu/drm/i915/intel_guc_log.c    |  9 ++++++++-
>>  5 files changed, 48 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_params.c
>> b/drivers/gpu/drm/i915/i915_params.c
>> index 14e2c2e..902bf2c 100644
>> --- a/drivers/gpu/drm/i915/i915_params.c
>> +++ b/drivers/gpu/drm/i915/i915_params.c
>> @@ -59,6 +59,7 @@ struct i915_params i915 __read_mostly = {
>>         .enable_guc_loading = 0,
>>         .enable_guc_submission = 0,
>>         .guc_log_level = -1,
>> +       .enable_guc_critical_logging = false,
>
>What's the point in having a log level if LOG_LEVEL_CRITICAL is not part of it?
>Please do explain why the current parameter does not cover this.
>-Chris

I agree with Chris. Apart from introducing a new parameter, this is also introducing the dependency on an existing one - guc_log_level. 

Anusha 
><Sagar> Agree that this could have been enumerated as another log level. Having
>it as log level simplifies other capture code too which I am seeing needs fix with
>current change. Will check if this can be changed in upcoming releases.
>
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