> -----Original Message----- > From: Jani Nikula <[email protected]> > Sent: Tuesday, June 16, 2026 1:31 PM > To: Murthy, Arun R <[email protected]>; [email protected]; > [email protected] > Cc: Murthy, Arun R <[email protected]>; Stephen Fuhry > <[email protected]> > Subject: Re: [PATCH v2 0/2] Unify fec enable/disable across the mst streams > > On Tue, 16 Jun 2026, Arun R Murthy <[email protected]> wrote: > > First version of the patch included only one patch i.e the ref count > > https://patchwork.freedesktop.org/series/167664/ > > > > Signed-off-by: Arun R Murthy <[email protected]> > > --- > > Arun R Murthy (2): > > drm/i915/mst: Unify fec_enable across mst streams > > drm/i915/display: Refcount for fec enable/disable > > > > drivers/gpu/drm/i915/display/intel_ddi.c | 58 ++++++++++++++++++ > > drivers/gpu/drm/i915/display/intel_ddi.h | 1 + > > drivers/gpu/drm/i915/display/intel_display_types.h | 3 + > > drivers/gpu/drm/i915/display/intel_dp_mst.c | 70 > ++++++++++++++++++++++ > > drivers/gpu/drm/i915/display/intel_modeset_setup.c | 6 ++ > > 5 files changed, 138 insertions(+) > > Okay, this may seem a bit unfair, since I haven't dug deep into the problem, > but > I really have a hard time believing this level of complexity is required for > FEC. > The problem is FEC is a link-wide property: DP_TP_CTL_FEC_ENABLE is a per-port HW bit, while crtc_state->fec_enable is per-stream. So synchronization across the mst stream is required. If not with refcount, maybe with get/put which eventually will be a kind of refcount but different name. Other alternative can be to add a logic in disble_fec() to check if there are any fec users within the mst siblings and if not then disable else return. But this only change may not help, will have to remove the crtc_state->fec_enable compare and HW readout as well.
Thanks and Regards, Arun R Murthy ------------------- > > BR, > Jani. > > > > --- > > base-commit: c585a0a7e48a48aca80f7c0acb7294c7bf301bb7 > > change-id: 20260616-fec-82a3d27e0f11 > > > > Best regards, > > -- > Jani Nikula, Intel
