From 32e823c63e90f7535ea1cc5311d25c0233e1456d Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Wed, 20 Sep 2017 15:59:34 -0700 Subject: [PATCH] drm/vc4: Reject HDMI modes with too high of clocks. Peter Robinson reported issues on Fedora with 4k monitors not having their modes filtered down to 1920x1080 on Raspberry Pi. v2: Fix vc5 typo in place of vc4. Cc: Peter Robinson Signed-off-by: Eric Anholt Link: https://patchwork.freedesktop.org/patch/msgid/20170920225935.14566-1-eric@anholt.net Acked-by: Daniel Vetter (v1) --- drivers/gpu/drm/vc4/vc4_hdmi.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 9a9a6b4acccf..ab3bcbe0bb93 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -693,7 +693,22 @@ static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder) } } +static enum drm_mode_status +vc4_hdmi_encoder_mode_valid(struct drm_encoder *crtc, + const struct drm_display_mode *mode) +{ + /* HSM clock must be 108% of the pixel clock. Additionally, + * the AXI clock needs to be at least 25% of pixel clock, but + * HSM ends up being the limiting factor. + */ + if (mode->clock > HSM_CLOCK_FREQ / (1000 * 108 / 100)) + return MODE_CLOCK_HIGH; + + return MODE_OK; +} + static const struct drm_encoder_helper_funcs vc4_hdmi_encoder_helper_funcs = { + .mode_valid = vc4_hdmi_encoder_mode_valid, .disable = vc4_hdmi_encoder_disable, .enable = vc4_hdmi_encoder_enable, }; -- 2.30.2