[Intel-gfx] [PATCH] drm/i915: Officially give up on seqno coherency

[Chris Wilson]

On Tue, Jun 23, 2015 at 01:52:27PM +0200, Daniel Vetter wrote:
> On Tue, Jun 23, 2015 at 01:05:41PM +0300, Jani Nikula wrote:
> > On Fri, 19 Jun 2015, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> > > We've never figured out the magic trick to make irq vs. seqno
> > > updates coherent, only tricks to make it work. And since
> > >
> > > commit 094f9a54e35500739da185cdb78f2e92fc379458
> > > Author: Chris Wilson <chris at chris-wilson.co.uk>
> > > Date:   Wed Sep 25 17:34:55 2013 +0100
> > >
> > >     drm/i915: Fix __wait_seqno to use true infinite timeouts
> > >
> > > we automatically fall back to an irq augmented with polling scheme
> > > after the first missed interrupt. There's really nothing else we can
> > > do, hence tune down the message to informational level. It's still
> > > useful for users in case it reliable preceedes a hard system hang.
> > >
> > > v2: Use NOTICE since it might be of value for bug reports (Chris).
> > >
> > > Cc: Mark Janes <mark.a.janes at intel.com>
> > > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: stable at vger.kernel.org
> > > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_irq.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > > index e6bb72dca3ff..5072fb49367e 100644
> > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > @@ -2946,8 +2946,8 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
> > >  					/* Issue a wake-up to catch stuck h/w. */
> > >  					if (!test_and_set_bit(ring->id, &dev_priv->gpu_error.missed_irq_rings)) {
> > >  						if (!(dev_priv->gpu_error.test_irq_rings & intel_ring_flag(ring)))
> > > -							DRM_ERROR("Hangcheck timer elapsed... %s idle\n",
> > > -								  ring->name);
> > > +							DRM_NOTICE("Hangcheck timer elapsed... %s idle\n",
> > 
> > drivers/gpu/drm/i915/i915_irq.c: In function ‘i915_hangcheck_elapsed’:
> > drivers/gpu/drm/i915/i915_irq.c:2949:8: error: implicit declaration of function ‘DRM_NOTICE’ [-Werror=implicit-function-declaration]
> >         DRM_NOTICE("Hangcheck timer elapsed... %s idle\n",

Nah. Just add it, we might as well use kmsg to our advantage. I'd also
like to not have all our kernel messages with [drm] as that gets very
confusing with multiple drivers.

Something like:

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 93794f9ab982..a7ea81d82bf5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -51,9 +51,14 @@
 #include <linux/kref.h>
 #include <linux/pm_qos.h>
 
+#include <drm/drmP.h>
+
 /* General customization:
  */
 
+#undef DRM_NAME
+#define DRM_NAME               "drm/i915"
+
 #define DRIVER_NAME            "i915"
 #define DRIVER_DESC            "Intel Graphics"
 #define DRIVER_DATE            "20150619"

would make me happier, but removing the "[]" from the messages would make
DRM more consistent with the rest of the kernel
-chris

-- 
Chris Wilson, Intel Open Source Technology Centre