Re: [PATCH 4/5] drm/i915: Let number of workarounds more clear

Chris Wilson
2014-09-26T12:58:18Z

On Fri, Sep 26, 2014 at 03:56:02PM +0300, Jani Nikula wrote:
> On Fri, 26 Sep 2014, Mika Kuoppala <mika.kuoppala@linux.intel.com> wrote:
> > Rodrigo Vivi <rodrigo.vivi@intel.com> writes:
> >
> >> This helps when including or removing cs workarounds.
> >> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> >> ---
> >> drivers/gpu/drm/i915/intel_ringbuffer.c | 16 ++++++++++++----
> >> 1 file changed, 12 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> >> index 7c3d17a..39fbea6 100644
> >> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> >> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> >> @@ -694,6 +694,7 @@ static int bdw_init_workarounds(struct intel_engine_cs *ring)
> >> int ret;
> >> struct drm_device *dev = ring->dev;
> >> struct drm_i915_private *dev_priv = dev->dev_private;
> >> + int wa_amount;
> >>
> >> /*
> >> * workarounds applied in this fn are part of register state context,
> >> @@ -704,10 +705,11 @@ static int bdw_init_workarounds(struct intel_engine_cs *ring)
> >> memset(dev_priv->intel_wa_regs, 0, sizeof(dev_priv->intel_wa_regs));
> >>
> >> /*
> >> - * update the number of dwords required based on the
> >> - * actual number of workarounds applied
> >> + * update the number of workarounds when adding or removing was
> >> + * in order the have propper dwords
> >> */
> >> - ret = intel_ring_begin(ring, 24);
> >> + wa_amount = 8;
> >> + ret = intel_ring_begin(ring, 3 * wa_amount);
> >> if (ret)
> >> return ret;
> >>
> >
> > I have a bit mixed feelings with this patch as I have tripped
> > around here myself recently.
> >
> > I think we should just drop this patch and use:
> > ret = intel_ring_begin(ring, 3 * <amount>) on the subsequent
> > patches that modify the amount.
> >
> > This way the intel_ring_begin will always be the one that
> > shows in a diff. And raises alarm if it doesnt. We don't want
> > this to be too transparent and looking too easy for the next reader.
> > As the reviewer is the only and last line of defense ensuring
> > symmetry between intel_ring_begin and amount of emits.
>
> Considering intel_ring_emit_wa() adds all the needed information to
> dev_priv->intel_wa_regs and dev_priv->num_wa_regs anyway, we could
> trivially split this into constructing dev_priv->intel_wa_regs first,

And only *once*.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre