Re: [PATCH v7 0/3] Panel Replay BW optimization

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2026-03-12 at 17:18 +0200, Imre Deak wrote:
> On Thu, Mar 12, 2026 at 10:05:35AM +0200, Hogander, Jouni wrote:
> > On Thu, 2026-03-12 at 10:30 +0530, Animesh Manna wrote:
> > > Unused bandwidth can be used by external display agents for Panel
> > > Replay
> > > enabled DP panel during idleness with link on. This patch series
> > > enabling the same.
> > 
> > Generic comment on this patch set. Maybe we should add one more
> > patch
> > with "Fixes" tag:
> > 
> > Fixes: e60cff453b82 ("drm/i915/dp: Enable DP tunnel BW allocation
> > mode")
> > Cc: Imre Deak <imre.deak@intel.com>
> > Cc: <stable@vger.kernel.org> # v6.9+
> 
> Why? As I understand the Panel Replay BW optimization on a DP
> tunneled
> link is an _optional_ feature, whereby the free BW can be used by the
> Thunderbolt protocol for other purposes than for the given display
> stream for which Panel Replay is enabled. IOW, it looks to me a valid
> configuration to enable Panel Replay on a DP tunneled link without
> enabling the Panel Replay BW optimization on it.

My original comment was about DP spec:

"
The DP Source device may optionally enable PR optimization with DP
tunneling. The device
shall query the Tunneling Bridge’s PR tunneling optimization capability
by way of the
Panel_Replay_Tunneling_Optimization_Support bit in the
DP_TUNNELING_CAPABILITIES
register (DPCD E000Dh[6]), and then enable PR only when the Tunneling
Bridge is capable.
"

That sounds like PR can be enabled only when Panel Replay Tunneling
Optimization is supported?

BR,
Jouni Högander

> 
> > This patch would just add:
> > 
> > if (intel_dp_tunnel_bw_alloc_is_enabled(intel_dp)) {
> > 	drm_dbg_kms(display->drm,
> > 		    "Panel Replay is disabled as DP tunneling
> > enabled\n");
> > 	return false;
> > }
> > 
> > into _panel_replay_compute_config. this could be first patch in
> > your
> > set. What do you think?
> > 
> > BR,
> > Jouni Högander
> > 
> > > 
> > > Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> > > 
> > > Animesh Manna (3):
> > >   drm/i915/display: Add drm helper to check pr optimization
> > > support
> > >   drm/i915/display: Panel Replay BW optimization for DP2.0
> > > tunneling
> > >   drm/i915/display: Disable Panel Replay for DP-tunneling without
> > >     optimization
> > > 
> > >  drivers/gpu/drm/display/drm_dp_tunnel.c       | 17 ++++++++++
> > >  .../gpu/drm/i915/display/intel_display_regs.h |  1 +
> > >  .../gpu/drm/i915/display/intel_dp_tunnel.c    | 14 +++++++++
> > >  .../gpu/drm/i915/display/intel_dp_tunnel.h    |  6 ++++
> > >  drivers/gpu/drm/i915/display/intel_psr.c      | 31
> > > +++++++++++++++++--
> > >  include/drm/display/drm_dp_tunnel.h           |  6 ++++
> > >  6 files changed, 73 insertions(+), 2 deletions(-)
> > > 
> >