target/linux/bcm27xx/patches-5.4/950-0612-drm-vc4-Alter-the-HDMI-state-machine-clock-calc-to-a.patch

   1 From 37b204f22778f51cad7bdf678d7574ff6d7508a6 Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.com>
   3 Date: Wed, 25 Mar 2020 18:22:40 +0000
   4 Subject: [PATCH] drm/vc4: Alter the HDMI state machine clock calc to
   5  allow for 1920x1200
   6
   7 Whilst the documentation for BCM2835 states that the HDMI state machine
   8 clock needs to be 108% of the pixel clock, other documentation says
   9 that it only has to be greater than the pixel clock. The firmware
  10 uses 101%, and that allows 1920x1200@60Hz to work within the
  11 constraint of the HSM clock being < 163.68MHz.
  12
  13 Adopt 101%, and increase the maximum pixel clock for vc4 to 162MHz
  14 so that it too supports 1920x1200@60.
  15
  16 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  17 ---
  18  drivers/gpu/drm/vc4/vc4_hdmi.c | 9 +++++----
  19  1 file changed, 5 insertions(+), 4 deletions(-)
  20
  21 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
  22 +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
  23 @@ -581,10 +581,11 @@ static void vc4_hdmi_encoder_enable(stru
  24         }
  25
  26         /*
  27 -        * The HSM rate needs to be at 108% of the pixel clock, with a
  28 -        * minimum of 108MHz.
  29 +        * The HSM rate needs to be slightly greater than the pixel clock, with
  30 +        * a minimum of 108MHz.
  31 +        * Use 101% as this is what the firmware uses.
  32          */
  33 -       hsm_rate = max_t(unsigned long, 108000000, (pixel_rate / 100) * 108);
  34 +       hsm_rate = max_t(unsigned long, 108000000, (pixel_rate / 100) * 101);
  35         ret = clk_set_rate(vc4_hdmi->hsm_clock, hsm_rate);
  36         if (ret) {
  37                 DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
  38 @@ -1730,7 +1731,7 @@ static int vc4_hdmi_dev_remove(struct pl
  39  }
  40
  41  static const struct vc4_hdmi_variant bcm2835_variant = {
  42 -       .max_pixel_clock        = 148500000,
  43 +       .max_pixel_clock        = 162000000,
  44         .audio_available        = true,
  45         .cec_available          = true,
  46         .registers              = vc4_hdmi_fields,