On Fri, Mar 31, 2023 at 12:39 AM Karol Herbst <kherbst@xxxxxxxxxx> wrote:
>
> This allows us to advertise more modes especially on HDR displays.
>
> Fixes using 4K@60 modes on my TV and main display both using a HDMI to DP
> adapter. Also fixes similiar issues for users running into this.
>
> Cc: stable@xxxxxxxxxxxxxxx # 5.10+
> Signed-off-by: Karol Herbst <kherbst@xxxxxxxxxx>
> ---
> drivers/gpu/drm/nouveau/dispnv50/disp.c | 32 +++++++++++++++++++++++++
> drivers/gpu/drm/nouveau/nouveau_dp.c | 8 ++++---
> 2 files changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index ed9d374147b8d..f28e47c161dd9 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -363,6 +363,35 @@ nv50_outp_atomic_check_view(struct drm_encoder *encoder,
> return 0;
> }
>
> +static void
> +nv50_outp_atomic_fix_depth(struct drm_encoder *encoder, struct drm_crtc_state *crtc_state)
> +{
> + struct nv50_head_atom *asyh = nv50_head_atom(crtc_state);
> + struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
> + struct drm_display_mode *mode = &asyh->state.adjusted_mode;
> + unsigned int max_rate, mode_rate;
> +
> + switch (nv_encoder->dcb->type) {
> + case DCB_OUTPUT_DP:
> + max_rate = nv_encoder->dp.link_nr * nv_encoder->dp.link_bw;
> +
> + /* we don't support more than 10 anyway */
> + asyh->or.bpc = max_t(u8, asyh->or.bpc, 10);
luckily I didn't push yet, but this has to be `min_t` :)
> +
> + /* reduce the bpc until it works out */
> + while (asyh->or.bpc > 6) {
> + mode_rate = DIV_ROUND_UP(mode->clock * asyh->or.bpc * 3, 8);
> + if (mode_rate <= max_rate)
> + break;
> +
> + asyh->or.bpc -= 2;
> + }
> + break;
> + default:
> + break;
> + }
> +}
> +
> static int
> nv50_outp_atomic_check(struct drm_encoder *encoder,
> struct drm_crtc_state *crtc_state,
> @@ -381,6 +410,9 @@ nv50_outp_atomic_check(struct drm_encoder *encoder,
> if (crtc_state->mode_changed || crtc_state->connectors_changed)
> asyh->or.bpc = connector->display_info.bpc;
>
> + /* We might have to reduce the bpc */
> + nv50_outp_atomic_fix_depth(encoder, crtc_state);
> +
> return 0;
> }
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index e00876f92aeea..d49b4875fc3c9 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -263,8 +263,6 @@ nouveau_dp_irq(struct work_struct *work)
> }
>
> /* TODO:
> - * - Use the minimum possible BPC here, once we add support for the max bpc
> - * property.
> * - Validate against the DP caps advertised by the GPU (we don't check these
> * yet)
> */
> @@ -276,7 +274,11 @@ nv50_dp_mode_valid(struct drm_connector *connector,
> {
> const unsigned int min_clock = 25000;
> unsigned int max_rate, mode_rate, ds_max_dotclock, clock = mode->clock;
> - const u8 bpp = connector->display_info.bpc * 3;
> + /* Check with the minmum bpc always, so we can advertise better modes.
> + * In particlar not doing this causes modes to be dropped on HDR
> + * displays as we might check with a bpc of 16 even.
> + */
> + const u8 bpp = 6 * 3;
>
> if (mode->flags & DRM_MODE_FLAG_INTERLACE && !outp->caps.dp_interlace)
> return MODE_NO_INTERLACE;
> --
> 2.39.2
>
