Re: [PATCH 4/8] drm/vc4: hdmi: Check and warn if we can't reach 4kp60 frequencies

Hi Maxime

On Thu, 25 Feb 2021 at 15:59, Maxime Ripard maxime@cerno.tech wrote:

In order to reach the frequencies needed to output at 594MHz, the firmware needs to be configured with the appropriate parameters in the config.txt file (enable_hdmi_4kp60 and force_turbo).

force_turbo isn't the right way to go about this as it permanently bumps all the clocks up, even if running the display at VGA.

Let's detect it at bind time, warn the user if we can't, and filter out the relevant modes.

Signed-off-by: Maxime Ripard maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_hdmi.c | 17 +++++++++++++++++ drivers/gpu/drm/vc4/vc4_hdmi.h | 8 ++++++++ 2 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index b5bc742993a4..f05f6da286f7 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -953,6 +953,9 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder, if (pixel_rate > vc4_hdmi->variant->max_pixel_clock) return -EINVAL;

•   if (vc4_hdmi->disable_4kp60 && (pixel_rate > HDMI_14_MAX_TMDS_CLK))
  

•           return -EINVAL;
  

•   vc4_state->pixel_rate = pixel_rate;
  
    return 0;
  

@@ -972,6 +975,9 @@ vc4_hdmi_encoder_mode_valid(struct drm_encoder *encoder, if ((mode->clock * 1000) > vc4_hdmi->variant->max_pixel_clock) return MODE_CLOCK_HIGH;

•   if (vc4_hdmi->disable_4kp60 && ((mode->clock * 1000) > HDMI_14_MAX_TMDS_CLK))
  

•           return MODE_CLOCK_HIGH;
  

•   return MODE_OK;
  

}

@@ -1986,6 +1992,17 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) vc4_hdmi->disable_wifi_frequencies = of_property_read_bool(dev->of_node, "wifi-2.4ghz-coexistence");

•   if (variant->max_pixel_clock == 600000000) {
  

•           struct vc4_dev *vc4 = to_vc4_dev(drm);
  

•           long max_rate = clk_get_max_rate(vc4->hvs->core_clk);
  

•           if (max_rate < 550000000) {
  

•                   drm_warn(drm, "The core clock cannot reach frequencies high enough to support 4k @ 60Hz.");
  

•                   drm_warn(drm, "Please change your config.txt file to add hdmi_enable_4kp60 and force_turbo");
  

Do we really want to warn in bind? Again you could have a VGA resolution monitor attached but that would trigger this warning. Can we warn (once) on processing the mode list and filtering out a clk

HDMI_14_MAX_TMDS_CLK mode instead?

And mentioning force_turbo is again wrong.

Dave

•                   vc4_hdmi->disable_4kp60 = true;
  

•           }
  

•   }
  

•   if (vc4_hdmi->variant->reset)
            vc4_hdmi->variant->reset(vc4_hdmi);
  
  

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h index 3cebd1fd00fc..3cd021136402 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.h +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h @@ -154,6 +154,14 @@ struct vc4_hdmi { */ bool disable_wifi_frequencies;

•   /*
  

•    * Even if HDMI0 on the RPi4 can output modes requiring a pixel
  

•    * rate higher than 297MHz, it needs some adjustments in the
  

•    * config.txt file to be able to do so and thus won't always be
  

•    * available.
  

•    */
  

•   bool disable_4kp60;
  

•   struct cec_adapter *cec_adap;
    struct cec_msg cec_rx_msg;
    bool cec_tx_ok;
  

-- 2.29.2