On Fri, 17 Jan 2020, Lee Shawn C <[email protected]> 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 <[email protected]>
> Cc: Ville Syrjälä <[email protected]>
> Cc: Maarten Lankhorst <[email protected]>
> Cc: Jani Nikula <[email protected]>
> Cc: Cooper Chiou <[email protected]>
> Cc: Sam McNally <[email protected]>
> Signed-off-by: Lee Shawn C <[email protected]>
> ---
> 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;
> +}
> +
Instead of this, please add a simple intel_lspcon.c function:
int lspcon_max_rate(struct intel_lspcon *lspcon);
that returns the max rate. Everything else can then be done in
intel_dp.c around this. The function gets simplified enough that you can
throw out the const ints and use the values directly.
> /* Optimize link config in order: max bpp, min clock, min lanes */
> static int
> intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
> @@ -1989,6 +2030,10 @@ intel_dp_compute_link_config_wide(struct intel_dp
> *intel_dp,
> for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) {
> int output_bpp = intel_dp_output_bpp(pipe_config, bpp);
>
> + /* Bypass th bpp if require bandwidth over HDMI spec when
> LSPCON active */
> + if (intel_dp_lspcon_exceed_bandwidth_limitation(intel_dp,
> pipe_config, output_bpp))
> + continue;
> +
The placing sticks out like a sore thumb. I think we need to filter out
the modes already in intel_dp_mode_valid(). This isn't all that
different from intel_dp_downstream_max_dotclock() is it?
> mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
> output_bpp);
But I guess since the mode valid limit is for 8 bpc, you'll also need a
check here? Maybe Ville has better ideas.
Here it would be something like:
if (lspcon->active && mode_rate > lspcon_max_rate(lscon))
continue;
BR,
Jani.
>
> diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c
> b/drivers/gpu/drm/i915/display/intel_lspcon.c
> index d807c5648c87..6952c5028fdf 100644
> --- a/drivers/gpu/drm/i915/display/intel_lspcon.c
> +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
> @@ -550,6 +550,11 @@ void lspcon_wait_pcon_mode(struct intel_lspcon *lspcon)
> lspcon_wait_mode(lspcon, DRM_LSPCON_MODE_PCON);
> }
>
> +int lspcon_get_mode(struct intel_lspcon *lspcon)
> +{
> + return lspcon_get_current_mode(lspcon);
> +}
> +
> bool lspcon_init(struct intel_digital_port *intel_dig_port)
> {
> struct intel_dp *dp = &intel_dig_port->dp;
> diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.h
> b/drivers/gpu/drm/i915/display/intel_lspcon.h
> index 37cfddf8a9c5..5ce9daef9708 100644
> --- a/drivers/gpu/drm/i915/display/intel_lspcon.h
> +++ b/drivers/gpu/drm/i915/display/intel_lspcon.h
> @@ -18,6 +18,7 @@ struct intel_lspcon;
> bool lspcon_init(struct intel_digital_port *intel_dig_port);
> void lspcon_resume(struct intel_lspcon *lspcon);
> void lspcon_wait_pcon_mode(struct intel_lspcon *lspcon);
> +int lspcon_get_mode(struct intel_lspcon *lspcon);
> void lspcon_write_infoframe(struct intel_encoder *encoder,
> const struct intel_crtc_state *crtc_state,
> unsigned int type,
--
Jani Nikula, Intel Open Source Graphics Center
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