[Intel-gfx] [RFC] drm/i915/guc: Keep GuC log disabled by default

[Lofstedt, Marta]

+ Daniel

> -----Original Message-----
> From: Wajdeczko, Michal
> Sent: Friday, January 19, 2018 2:49 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: Wajdeczko, Michal <Michal.Wajdeczko at intel.com>; Chris Wilson
> <chris at chris-wilson.co.uk>; Saarinen, Jani <jani.saarinen at intel.com>;
> Sarvela, Tomi P <tomi.p.sarvela at intel.com>; Lofstedt, Marta
> <marta.lofstedt at intel.com>; Winiarski, Michal <michal.winiarski at intel.com>
> Subject: [RFC] drm/i915/guc: Keep GuC log disabled by default
> 
> It looks that GuC log functionality is not fully functional yet and causes issues
> when enabled by auto(-1) modparam on debug builds.
> 
> [   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.
> 
> Fixes: 0ed87953532652 ("drm/i915/guc: Redefine guc_log_level modparam
> values")
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jani Saarinen <jani.saarinen at intel.com>
> Cc: Tomi Sarvela <tomi.p.sarvela at intel.com>
> Cc: Marta Lofstedt <marta.lofstedt at intel.com>
> Cc: Michal Winiarski <michal.winiarski at 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