[Intel-gfx] [PATCH 5/5] drm/i915/bdw: Add support for DRRS to switch RR

[Chris Wilson]

On Wed, Dec 18, 2013 at 01:54:56PM +0530, Vandana Kannan wrote:
> On Dec-17-2013 6:00 PM, Chris Wilson wrote:
> > On Tue, Dec 17, 2013 at 10:58:27AM +0530, Vandana Kannan wrote:
> >> For Broadwell, there is one instance of Transcoder MN values per transcoder.
> >> For dynamic switching between multiple refreshr rates, M/N values may be
> >> reprogrammed on the fly. Link N programming triggers update of all data and
> >> link M & N registers and the new M/N values will be used in the next frame
> >> that is output.
> >>
> >> Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
> >> Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/intel_dp.c |   23 +++++++++++++++++++----
> >>  1 file changed, 19 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> >> index 209be3c..183cfd7 100644
> >> --- a/drivers/gpu/drm/i915/intel_dp.c
> >> +++ b/drivers/gpu/drm/i915/intel_dp.c
> >> @@ -798,9 +798,15 @@ intel_dp_set_m2_n2(struct intel_crtc *crtc, struct intel_link_m_n *m_n)
> >>  	struct drm_i915_private *dev_priv = dev->dev_private;
> >>  	enum transcoder transcoder = crtc->config.cpu_transcoder;
> >>  
> >> -	if (INTEL_INFO(dev)->gen >= 5 && INTEL_INFO(dev)->gen < 8) {
> >> +	if (INTEL_INFO(dev)->gen >= 8) {
> >> +		I915_WRITE(PIPE_DATA_M1(transcoder),
> >> +			TU_SIZE(m_n->tu) | m_n->gmch_m);
> >> +		I915_WRITE(PIPE_DATA_N1(transcoder), m_n->gmch_n);
> >> +		I915_WRITE(PIPE_LINK_M1(transcoder), m_n->link_m);
> >> +		I915_WRITE(PIPE_LINK_N1(transcoder), m_n->link_n);
> >> +	} else if (INTEL_INFO(dev)->gen >= 5 && INTEL_INFO(dev)->gen < 8) {
> > 
> > Ouch. Double ouch later.
> > -Chris
> > 
> We are looking to write in M1/N1 registers for BDW and M2/N2 registers
> for HSW and below. What is your suggestion on how to implement this ?

  if (gen >= 8) {
  } else if (gen >= 5) {
  }

Or as you use gen >= 5 && gen < 8 elsewhere, a feature macro would be
even more sensible, HAS_DRRS().
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre