Re: [PATCH] drm/i915: Flush the PTEs after updating them before suspend

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

On Thu, 18 Sep 2014, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Thu, Sep 18, 2014 at 07:03:32AM +0100, Chris Wilson wrote:
>> As we use WC updates of the PTE, we are responsible for notifying the
>> hardware when to flush its TLBs. Do so after we zap all the PTEs before
>> suspend (and the BIOS tries to read our GTT).
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82340
>> Tested-by: ming.yao@intel.com
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>
> This fixes a regression from the (functional) revert
>
>     drm/i915: Undo gtt scratch pte unmapping again
>
>     It apparently blows up on some machines. This functionally reverts
>
>     commit 828c79087cec61eaf4c76bb32c222fbe35ac3930
>     Author: Ben Widawsky <benjamin.widawsky@intel.com>
>     Date:   Wed Oct 16 09:21:30 2013 -0700
>
>         drm/i915: Disable GGTT PTEs on GEN6+ suspend
>
>     Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=64841
>     Reported-and-Tested-by: Brad  Jackson <bjackson0971@gmail.com>
>     Cc: stable@vger.kernel.org
>     Cc: Takashi Iwai <tiwai@suse.de>
>     Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
>     Cc: Todd Previte <tprevite@gmail.com>
>     Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>     Signed-off-by: Dave Airlie <airlied@redhat.com>
>
> Cc: stable@vger.kernel.org
> Cc: Takashi Iwai <tiwai@suse.de>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Todd Previte <tprevite@gmail.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
> When fixing regressions pls don't forget to cite the offending commit and
> cc all relevant people. Jani, please amend the commit with the above when
> merging.

The patch fails to apply on any branch. Please refresh.

BR,
Jani.


>
> Aside: This means that the bios writes to various ranges in the gtt, so I
> still think we need to insert ptes pointing at stolen, too. Otherwise
> we've simply reduced the chances for this bug to destroy important
> something I think.
> -Daniel
>
>
>> ---
>>  drivers/gpu/drm/i915/i915_gem_gtt.c | 14 +++++++++++++-
>>  1 file changed, 13 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> index 97ba18846761..aa81b217fac0 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> @@ -1234,6 +1234,16 @@ void i915_check_and_clear_faults(struct drm_device *dev)
>>  	POSTING_READ(RING_FAULT_REG(RCS_ENGINE(dev_priv)));
>>  }
>>  
>> +static void i915_ggtt_flush(struct drm_i915_private *dev_priv)
>> +{
>> +	if (INTEL_INFO(dev_priv)->gen < 6) {
>> +		intel_gtt_chipset_flush();
>> +	} else {
>> +		I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
>> +		POSTING_READ(GFX_FLSH_CNTL_GEN6);
>> +	}
>> +}
>> +
>>  void i915_gem_suspend_gtt_mappings(struct drm_device *dev)
>>  {
>>  	struct drm_i915_private *dev_priv = dev->dev_private;
>> @@ -1250,6 +1260,8 @@ void i915_gem_suspend_gtt_mappings(struct drm_device *dev)
>>  				       dev_priv->gtt.base.start,
>>  				       dev_priv->gtt.base.total,
>>  				       true);
>> +
>> +	i915_ggtt_flush(dev_priv);
>>  }
>>  
>>  void i915_gem_restore_gtt_mappings(struct drm_device *dev)
>> @@ -1302,7 +1314,7 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
>>  		gen6_write_pdes(container_of(vm, struct i915_hw_ppgtt, base));
>>  	}
>>  
>> -	i915_gem_chipset_flush(dev);
>> +	i915_ggtt_flush(dev_priv);
>>  }
>>  
>>  int i915_gem_gtt_prepare_object(struct drm_i915_gem_object *obj)
>> -- 
>> 2.1.0
>> 
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Jani Nikula, Intel Open Source Technology Center