> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Ville Syrjala
> Sent: Tuesday, March 22, 2022 5:30 PM
> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: [PATCH v2 08/12] drm/i915/dp: Rework HDMI DFP TMDS clock
> handling
>
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Rework the HDMI DFP TMDS clock checks to also check at 8bpc.
> Previously we only checked the deep color cases. But I suppose a sink could
> potentially declare "4:2:0 also" modes that only actually fit within its own limits
> when using 4:2:0. Even if that is too nuts to be real there is no real harm in running
> through the full checks for everything.
Yeah this should be ok. Changes look Good to me.
Reviewed-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 35 ++++++++++++++++++-------
> 1 file changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index a78522dc9b3c..436d0b0f0b76 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1163,16 +1163,28 @@ static bool intel_dp_is_ycbcr420(struct intel_dp
> *intel_dp,
> intel_dp->dfp.ycbcr_444_to_420);
> }
>
> -static bool intel_dp_hdmi_bpc_possible(struct intel_dp *intel_dp,
> - const struct intel_crtc_state *crtc_state,
> - int bpc)
> +static int intel_dp_hdmi_compute_bpc(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state,
> + int bpc)
> {
> bool ycbcr420_output = intel_dp_is_ycbcr420(intel_dp, crtc_state);
> int clock = crtc_state->hw.adjusted_mode.crtc_clock;
>
> - return intel_hdmi_bpc_possible(crtc_state, bpc,
> - intel_dp->has_hdmi_sink, ycbcr420_output) &&
> - intel_dp_tmds_clock_valid(intel_dp, clock, bpc, ycbcr420_output)
> == MODE_OK;
> + /*
> + * Current bpc could already be below 8bpc due to
> + * FDI bandwidth constraints or other limits.
> + * HDMI minimum is 8bpc however.
> + */
> + bpc = max(bpc, 8);
> +
> + for (; bpc >= 8; bpc -= 2) {
> + if (intel_hdmi_bpc_possible(crtc_state, bpc,
> + intel_dp->has_hdmi_sink,
> ycbcr420_output) &&
> + intel_dp_tmds_clock_valid(intel_dp, clock, bpc, ycbcr420_output)
> == MODE_OK)
> + return bpc;
> + }
> +
> + return -EINVAL;
> }
>
> static int intel_dp_max_bpp(struct intel_dp *intel_dp, @@ -1188,10 +1200,13 @@
> static int intel_dp_max_bpp(struct intel_dp *intel_dp,
> bpc = min_t(int, bpc, intel_dp->dfp.max_bpc);
>
> if (intel_dp->dfp.min_tmds_clock) {
> - for (; bpc >= 10; bpc -= 2) {
> - if (intel_dp_hdmi_bpc_possible(intel_dp, crtc_state, bpc))
> - break;
> - }
> + int max_hdmi_bpc;
> +
> + max_hdmi_bpc = intel_dp_hdmi_compute_bpc(intel_dp, crtc_state,
> bpc);
> + if (max_hdmi_bpc < 0)
> + return 0;
> +
> + bpc = min(bpc, max_hdmi_bpc);
> }
>
> bpp = bpc * 3;
> --
> 2.34.1
