On Fri, Jan 17, 2020 at 09:47:17PM +0800, Lee Shawn C wrote:
> While mode setting, driver would calculate mode rate based on
> resolution and bpp. And choose the best bpp that did not exceed
> DP bandwidtd.
>
> But LSPCON had more restriction due to it convert DP to HDMI.
> Driver should respect HDMI's bandwidth limitation if LSPCON
> was active. This change would ignore the bpp when its required
> output bandwidth already over HDMI 2.0 or 1.4 spec.
>
> Cc: Imre Deak <imre.deak@xxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Cooper Chiou <cooper.chiou@xxxxxxxxx>
> Cc: Sam McNally <sammc@xxxxxxxxxx>
> Signed-off-by: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 45 +++++++++++++++++++++
> drivers/gpu/drm/i915/display/intel_lspcon.c | 5 +++
> drivers/gpu/drm/i915/display/intel_lspcon.h | 1 +
> 3 files changed, 51 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index c7424e2a04a3..c27d3e7ac219 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1976,6 +1976,47 @@ static int intel_dp_output_bpp(const struct intel_crtc_state *crtc_state, int bp
> return bpp;
> }
>
> +static bool
> +intel_dp_lspcon_exceed_bandwidth_limitation(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + int bpp)
> +{
> + struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
> + struct intel_connector *connector = intel_dp->attached_connector;
> + const struct drm_display_info *info = &connector->base.display_info;
> + enum drm_lspcon_mode lspcon_current_mode = lspcon_get_mode(lspcon);
> + const int pcon_mode_max_tmds_clock = 600000;
> + const int ls_mode_max_tmds_clock = 340000;
> + int mode_rate, max_tmds_clock = pcon_mode_max_tmds_clock;
> +
> + if (lspcon->active) {
> + switch (bpp) {
> + case 36:
> + mode_rate = pipe_config->hw.adjusted_mode.crtc_clock * 3 / 2;
> + break;
> + case 30:
> + mode_rate = pipe_config->hw.adjusted_mode.crtc_clock * 5 / 4;
> + break;
> + case 24:
> + default:
> + mode_rate = pipe_config->hw.adjusted_mode.crtc_clock;
> + break;
> + }
> +
> + if (lspcon_current_mode == DRM_LSPCON_MODE_LS)
> + max_tmds_clock = ls_mode_max_tmds_clock;
> +
> + if (info->max_tmds_clock)
> + max_tmds_clock = min(max_tmds_clock,
> + info->max_tmds_clock);
> +
> + if (mode_rate > max_tmds_clock)
> + return true;
> + }
> +
> + return false;
> +}
That's rather ad-hoc. I've been cooking a much more generic solution to
deal with all kinds of DP DFPs. It should handle the TMDS limits for
HDMI/DVI DFPs (and on board LSPCON too IIRC), as well as hooking up
YUV 444->420 conversion if supported by the dongle (though those old
on board LSPCON chips do that differently so shouldn't affect them).
Rebased version available here:
git://github.com/vsyrjala/linux.git dp_downstream_ports_4
One caveat is that I've not re-tested it in maybe half a year,
so not entirely sure it still works 100%.
--
Ville Syrjälä
Intel
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