Most of the reason I'm asking for an RFC here is because this code pulls a lot of code out of i915 and into shared DP helpers.
Anyway-nouveau's HPD related code has been collecting dust for a while. Other then the occasional runtime PM related and MST related fixes, we're missing a lot of nice things that have been added to DRM since this was originally written. Additionally, the code is just really unoptimized in general:
* We handle connector probing in the same context that we handle short IRQs in for DP, which means connector probing could potentially block ESI handling for MST * When we receive a hotplug event from a connector, we reprobe every single connector instead of just the connector that was hotplugged * Additionally because of the above reason, combined with the fact I had the bad idea of reusing some of the MST locks when I last rewrote nouveau's DP MST detection, trying to handle any other events that require short HPD IRQs is a bit awkward to actually implement. * We don't actually properly check whether EDIDs change or not when reprobing, which means we basically send out a hotplug event every single time we receive one even if nothing has changed
Additionally, the code for handling DP that we have in nouveau is also quite unoptimized in general, doesn't use a lot of helpers that have been added since it was written, and is also missing quite a number of features:
* Downstream port capability probing * Extended DPRX cap parsing * SINK_COUNT handling for hpd on dongles
Luckily for us - all of these are implemented in i915 already. Since there's no reason for us to reinvent the wheel, and having more shared code is always nice, I decided to take the opportunity to extract the code for all of these features from i915 into a set of core DP helpers, which both i915 and nouveau (and hopefully other drivers in the future) can use.
As well, this patch series also addesses the other general connector probing related issues I mentioned above, along with rewriting how we handle MST probing so we don't hit any surprise locking design issues in the future.
As a note - most of this work is motivated by the fact that I'm planning on adding max_bpc/output_bpc prop support, DSC support (for both MST and SST, along with proper helpers for handling bandwidth limitations and DSC), and fallback link retraining. I figured I might as clean this code up and implement missing DP features like the ones mentioned here before moving on to those tasks.
Lyude Paul (20): drm/nouveau/kms: Fix some indenting in nouveau_dp_detect() drm/nouveau/kms/nv50-: Remove open-coded drm_dp_read_desc() drm/nouveau/kms/nv50-: Just use drm_dp_dpcd_read() in nouveau_dp.c drm/nouveau/kms/nv50-: Use macros for DP registers in nouveau_dp.c drm/nouveau/kms: Don't clear DP_MST_CTRL DPCD in nv50_mstm_new() drm/nouveau/kms: Search for encoders' connectors properly drm/nouveau/kms/nv50-: Use drm_dp_dpcd_(readb|writeb)() in nv50_sor_disable() drm/nouveau/kms/nv50-: Refactor and cleanup DP HPD handling drm/i915/dp: Extract drm_dp_has_mst() drm/nouveau/kms: Use new drm_dp_has_mst() helper for checking MST caps drm/nouveau/kms: Move drm_dp_cec_unset_edid() into nouveau_connector_detect() drm/nouveau/kms: Only use hpd_work for reprobing in HPD paths drm/i915/dp: Extract drm_dp_downstream_read_info() drm/nouveau/kms/nv50-: Use downstream DP clock limits for mode validation drm/i915/dp: Extract drm_dp_has_sink_count() drm/i915/dp: Extract drm_dp_get_sink_count() drm/nouveau/kms/nv50-: Add support for DP_SINK_COUNT drm/nouveau/kms: Don't change EDID when it hasn't actually changed drm/i915/dp: Extract drm_dp_read_dpcd_caps() drm/nouveau/kms: Start using drm_dp_read_dpcd_caps()
drivers/gpu/drm/drm_dp_helper.c | 167 +++++++++++ drivers/gpu/drm/i915/display/intel_dp.c | 124 ++------ drivers/gpu/drm/i915/display/intel_dp.h | 1 - drivers/gpu/drm/i915/display/intel_lspcon.c | 2 +- drivers/gpu/drm/nouveau/dispnv04/dac.c | 2 +- drivers/gpu/drm/nouveau/dispnv04/dfp.c | 7 +- drivers/gpu/drm/nouveau/dispnv04/disp.c | 24 +- drivers/gpu/drm/nouveau/dispnv04/disp.h | 4 + drivers/gpu/drm/nouveau/dispnv04/tvnv04.c | 2 +- drivers/gpu/drm/nouveau/dispnv04/tvnv17.c | 2 +- drivers/gpu/drm/nouveau/dispnv50/disp.c | 305 +++++++++++--------- drivers/gpu/drm/nouveau/nouveau_connector.c | 132 ++++----- drivers/gpu/drm/nouveau/nouveau_connector.h | 1 + drivers/gpu/drm/nouveau/nouveau_display.c | 72 ++++- drivers/gpu/drm/nouveau/nouveau_display.h | 3 +- drivers/gpu/drm/nouveau/nouveau_dp.c | 211 +++++++++++--- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 +- drivers/gpu/drm/nouveau/nouveau_drv.h | 2 + drivers/gpu/drm/nouveau/nouveau_encoder.h | 48 ++- include/drm/drm_dp_helper.h | 15 +- include/drm/drm_dp_mst_helper.h | 22 ++ 21 files changed, 761 insertions(+), 389 deletions(-)