On Wed, Apr 13, 2011 at 07:21:30PM -0700, Ben Widawsky wrote: > On Tue, Apr 12, 2011 at 09:31:51PM +0100, Chris Wilson wrote: > > The read back of the available FIFO entries is vital for system > > stability, but extremely costly. However, we only need a guide so as to > > avoid eating into the reserved entries and since we are the only > > consumer we can cache the read of the count from the last write. > > > > Signed-off-by: Chris Wilson <[email protected]> > > --- > > drivers/gpu/drm/i915/i915_drv.c | 14 +++++++++----- > > drivers/gpu/drm/i915/i915_drv.h | 1 + > > 2 files changed, 10 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.c > > b/drivers/gpu/drm/i915/i915_drv.c > > index c416c1d..1146abd 100644 > > --- a/drivers/gpu/drm/i915/i915_drv.c > > +++ b/drivers/gpu/drm/i915/i915_drv.c > > @@ -287,12 +287,16 @@ void __gen6_gt_force_wake_put(struct drm_i915_private > > *dev_priv) > > > > void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv) > > { > > - int loop = 500; > > - u32 fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES); > > - while (fifo < 20 && loop--) { > > - udelay(10); > > - fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES); > > + if (dev_priv->gt_fifo_count < 20 ) { > > + int loop = 500; > > + u32 fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES); > > + while (fifo < 20 && loop--) { > > + udelay(10); > > + fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES); > > + } > > + dev_priv->gt_fifo_count = fifo; > > } > > + dev_priv->gt_fifo_count--; > > } > > > > static int i915_drm_freeze(struct drm_device *dev) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h > > b/drivers/gpu/drm/i915/i915_drv.h > > index 2f45228..c837e10 100644 > > --- a/drivers/gpu/drm/i915/i915_drv.h > > +++ b/drivers/gpu/drm/i915/i915_drv.h > > @@ -268,6 +268,7 @@ typedef struct drm_i915_private { > > int relative_constants_mode; > > > > void __iomem *regs; > > + u32 gt_fifo_count; > > > > struct intel_gmbus { > > struct i2c_adapter adapter; > > I'm sure you noticed that we have seriously problem both here and in the > put()/get() if the condition doesn't clear up in loop number of times. > > I'd probably add a WARN(!loop, "uh oh"), but the patch is better than > what is there currently, so I'm okay either way.
Post-decrement, and check fifo, so... (loop < 0 && !fifo) > > Reviewed-by: Ben Widawsky <[email protected]> > _______________________________________________ > Intel-gfx mailing list > [email protected] > http://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
