| Message ID | 1302640318-23165-24-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <chris@chris-wilson.co.uk> > --- > 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. Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
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 <chris@chris-wilson.co.uk> > > --- > > 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 <ben@bwidawsk.net> > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
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;
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 <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_drv.c | 14 +++++++++----- drivers/gpu/drm/i915/i915_drv.h | 1 + 2 files changed, 10 insertions(+), 5 deletions(-)