target/linux/brcm2708/patches-4.14/950-0179-drm-vc4-Reject-HDMI-modes-with-too-high-of-clocks.patch

   1 From ee3cf448adf29e8948c40d251f87d87a9817515c Mon Sep 17 00:00:00 2001
   2 From: Eric Anholt <eric@anholt.net>
   3 Date: Wed, 20 Sep 2017 15:59:34 -0700
   4 Subject: [PATCH 179/454] drm/vc4: Reject HDMI modes with too high of clocks.
   5
   6 Peter Robinson reported issues on Fedora with 4k monitors not having
   7 their modes filtered down to 1920x1080 on Raspberry Pi.
   8
   9 v2: Fix vc5 typo in place of vc4.
  10
  11 Cc: Peter Robinson <pbrobinson@redhat.com>
  12 Signed-off-by: Eric Anholt <eric@anholt.net>
  13 Link: https://patchwork.freedesktop.org/patch/msgid/20170920225935.14566-1-eric@anholt.net
  14 Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v1)
  15 (cherry picked from commit 32e823c63e90f7535ea1cc5311d25c0233e1456d)
  16 ---
  17  drivers/gpu/drm/vc4/vc4_hdmi.c | 15 +++++++++++++++
  18  1 file changed, 15 insertions(+)
  19
  20 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
  21 +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
  22 @@ -695,7 +695,22 @@ static void vc4_hdmi_encoder_enable(stru
  23         }
  24  }
  25
  26 +static enum drm_mode_status
  27 +vc4_hdmi_encoder_mode_valid(struct drm_encoder *crtc,
  28 +                           const struct drm_display_mode *mode)
  29 +{
  30 +       /* HSM clock must be 108% of the pixel clock.  Additionally,
  31 +        * the AXI clock needs to be at least 25% of pixel clock, but
  32 +        * HSM ends up being the limiting factor.
  33 +        */
  34 +       if (mode->clock > HSM_CLOCK_FREQ / (1000 * 108 / 100))
  35 +               return MODE_CLOCK_HIGH;
  36 +
  37 +       return MODE_OK;
  38 +}
  39 +
  40  static const struct drm_encoder_helper_funcs vc4_hdmi_encoder_helper_funcs = {
  41 +       .mode_valid = vc4_hdmi_encoder_mode_valid,
  42         .disable = vc4_hdmi_encoder_disable,
  43         .enable = vc4_hdmi_encoder_enable,
  44  };