Re: [RFC] drm/i915/guc: Keep GuC log disabled by default

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 19 Jan 2018, Michał Winiarski <michal.winiarski@intel.com> wrote:
> On Fri, Jan 19, 2018 at 12:49:26PM +0000, Michal Wajdeczko wrote:
>> It looks that GuC log functionality is not fully functional yet and
>> causes issues when enabled by auto(-1) modparam on debug builds.

This could use a better explanation. Now it seems like you're just
sweeping things under the carpet.

>> 
>> [   30.062893] ======================================================
>> [   30.062894] WARNING: possible circular locking dependency detected
>> [   30.062895] 4.15.0-rc8-CI-CI_DRM_3648+ #1 Tainted: G     U
>> [   30.062896] ------------------------------------------------------
>> [   30.062897] debugfs_test/1268 is trying to acquire lock:
>> [   30.062898]  (&dev->struct_mutex){+.+.}, at: [<00000000e4213449>] i915_mutex_lock_interruptible+0x47/0x130 [i915]
>> [   30.062921]
>>                but task is already holding lock:
>> [   30.062921]  (&mm->mmap_sem){++++}, at: [<00000000dd7adc93>] __do_page_fault+0x106/0x560
>> [   30.062924]
>>                which lock already depends on the new lock.
>> 
>
> I'd leave the lockdep splat out of here, since that's just the tip of the
> iceberg :)
>
>> Fixes: 0ed87953532652 ("drm/i915/guc: Redefine guc_log_level modparam values")
>
> s/Fixes/References

References should generally reference URIs I think.

BR,
Jani.


>
> It allows us to get test results while we're fixing the logging issues, so:
>
> Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
>
> -Michał
>
>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Jani Saarinen <jani.saarinen@intel.com>
>> Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
>> Cc: Marta Lofstedt <marta.lofstedt@intel.com>
>> Cc: Michal Winiarski <michal.winiarski@intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_params.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
>> index c963603..430f5f9 100644
>> --- a/drivers/gpu/drm/i915/i915_params.h
>> +++ b/drivers/gpu/drm/i915/i915_params.h
>> @@ -48,7 +48,7 @@
>>  	param(int, enable_ips, 1) \
>>  	param(int, invert_brightness, 0) \
>>  	param(int, enable_guc, 0) \
>> -	param(int, guc_log_level, -1) \
>> +	param(int, guc_log_level, 0) \
>>  	param(char *, guc_firmware_path, NULL) \
>>  	param(char *, huc_firmware_path, NULL) \
>>  	param(int, mmio_debug, 0) \
>> -- 
>> 1.9.1
>> 
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-- 
Jani Nikula, Intel Open Source Technology Center
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