On Sat, 8 Jul 2023 at 07:59, Lyude Paul <lyude@xxxxxxxxxx> wrote: > > Currently we use the drm_dp_dpcd_read_caps() helper in the DRM side of > nouveau in order to read the DPCD of a DP connector, which makes sure we do > the right thing and also check for extended DPCD caps. However, it turns > out we're not currently doing this on the nvkm side since we don't have > access to the drm_dp_aux structure there - which means that the DRM side of > the driver and the NVKM side can end up with different DPCD capabilities > for the same connector. > > Ideally to fix this, we want to start setting up the drm_dp_aux device in > NVKM before we've made contact with the DRM side - which should be pretty > easy to accomplish (I'm already working on it!). Until then however, let's > workaround this problem by porting a copy of drm_dp_read_dpcd_caps() into > NVKM - which should fix this issue. I wouldn't worry about this. I'm moving basically everything to the DRM side of the driver for the GSP work anyway. Ben. > > Issue: https://gitlab.freedesktop.org/drm/nouveau/-/issues/211 > Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> > --- > drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c | 48 ++++++++++++++++++- > 1 file changed, 47 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c > index 40c8ea43c42f..b8ac66b4a2c4 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c > +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c > @@ -26,6 +26,8 @@ > #include "head.h" > #include "ior.h" > > +#include <drm/display/drm_dp.h> > + > #include <subdev/bios.h> > #include <subdev/bios/init.h> > #include <subdev/gpio.h> > @@ -634,6 +636,50 @@ nvkm_dp_enable_supported_link_rates(struct nvkm_outp *outp) > return outp->dp.rates != 0; > } > > +/* XXX: This is a big fat hack, and this is just drm_dp_read_dpcd_caps() > + * converted to work inside nvkm. This is a temporary holdover until we start > + * passing the drm_dp_aux device through NVKM > + */ > +static int > +nvkm_dp_read_dpcd_caps(struct nvkm_outp *outp) > +{ > + struct nvkm_i2c_aux *aux = outp->dp.aux; > + u8 dpcd_ext[DP_RECEIVER_CAP_SIZE]; > + int ret; > + > + ret = nvkm_rdaux(aux, DPCD_RC00_DPCD_REV, outp->dp.dpcd, DP_RECEIVER_CAP_SIZE); > + if (ret < 0) > + return ret; > + > + /* > + * Prior to DP1.3 the bit represented by > + * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved. > + * If it is set DP_DPCD_REV at 0000h could be at a value less than > + * the true capability of the panel. The only way to check is to > + * then compare 0000h and 2200h. > + */ > + if (!(outp->dp.dpcd[DP_TRAINING_AUX_RD_INTERVAL] & > + DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT)) > + return 0; > + > + ret = nvkm_rdaux(aux, DP_DP13_DPCD_REV, dpcd_ext, sizeof(dpcd_ext)); > + if (ret < 0) > + return ret; > + > + if (outp->dp.dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) { > + OUTP_DBG(outp, "Extended DPCD rev less than base DPCD rev (%d > %d)\n", > + outp->dp.dpcd[DP_DPCD_REV], dpcd_ext[DP_DPCD_REV]); > + return 0; > + } > + > + if (!memcmp(outp->dp.dpcd, dpcd_ext, sizeof(dpcd_ext))) > + return 0; > + > + memcpy(outp->dp.dpcd, dpcd_ext, sizeof(dpcd_ext)); > + > + return 0; > +} > + > void > nvkm_dp_enable(struct nvkm_outp *outp, bool auxpwr) > { > @@ -689,7 +735,7 @@ nvkm_dp_enable(struct nvkm_outp *outp, bool auxpwr) > memset(outp->dp.lttpr, 0x00, sizeof(outp->dp.lttpr)); > } > > - if (!nvkm_rdaux(aux, DPCD_RC00_DPCD_REV, outp->dp.dpcd, sizeof(outp->dp.dpcd))) { > + if (!nvkm_dp_read_dpcd_caps(outp)) { > const u8 rates[] = { 0x1e, 0x14, 0x0a, 0x06, 0 }; > const u8 *rate; > int rate_max; > -- > 2.40.1 >
