[Intel-gfx] [PATCH] drm/i915/gen9: fix error path in intel_init_workaround_bb

[Chris Wilson]

On Tue, Jun 23, 2015 at 06:18:21PM +0300, Imre Deak wrote:
> On ti, 2015-06-23 at 16:13 +0100, Siluvery, Arun wrote:
> > On 23/06/2015 15:36, Imre Deak wrote:
> > > On ti, 2015-06-23 at 15:31 +0100, Chris Wilson wrote:
> > >> On Tue, Jun 23, 2015 at 05:26:13PM +0300, Imre Deak wrote:
> > >>> On the GEN!=8 error path we call kmap_atomic() which returns in atomic
> > >>> context and then lrc_destroy_wa_ctx_obj() which can be called only in
> > >>> process context. Fix this by preserving the correct cleanup order on
> > >>> this error path.
> > >>>
> > >>> Also convert the WARN to DRM_ERROR the stack trace isn't really useful.
> > >>>
> > >>> Signed-off-by: Imre Deak <imre.deak at intel.com>
> > >>> ---
> > >>>   drivers/gpu/drm/i915/intel_lrc.c | 10 +++++++---
> > >>>   1 file changed, 7 insertions(+), 3 deletions(-)
> > >>>
> > >>> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> > >>> index 1b50dd7..8bff1a2 100644
> > >>> --- a/drivers/gpu/drm/i915/intel_lrc.c
> > >>> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> > >>> @@ -1289,10 +1289,14 @@ static int intel_init_workaround_bb(struct intel_engine_cs *ring)
> > >>>   		if (ret)
> > >>>   			goto out;
> > >>>   	} else {
> > >>> -		WARN(INTEL_INFO(ring->dev)->gen >= 8,
> > >>> -		     "WA batch buffer is not initialized for Gen%d\n",
> > >>> -		     INTEL_INFO(ring->dev)->gen);
> > >>> +		if (INTEL_INFO(ring->dev)->gen >= 8)
> > >>> +			DRM_ERROR("WA batch buffer is not initialized for Gen%d\n",
> > >>> +				  INTEL_INFO(ring->dev)->gen);
> > >>> +
> > >>
> > >> Do this test upfront, then we don't have multiple error paths.
> > >> http://paste.debian.net/255769
> > >
> > > I didn't bother moving it, I suppose GEN9 support will be added soon
> > > anyway and we get a bit more test coverage on GEN9 meanwhile. But if you
> > > insist I can move it.
> > 
> > Hi Imre,
> > 
> > I sent the following patch with the changes suggested by Chris.
> > https://patchwork.kernel.org/patch/6661891/
> > Since you sent it first, my patch can be ignored if your patch is updated.
> 
> I'm fine applying your patch, but I would ask to convert the WARN to
> DRM_ERROR. The stack trace doesn't add much to the error message and the
> WARN is needlessly verbose now on BXT,SKL..

I presumed Arun choose WARN because we are missing w/a and wanted
someone to step forward and prove the fixes?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre