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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 <pbrobinson@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20170920225935.14566-1-eric@anholt.net
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v1)
This commit is contained in:
Eric Anholt 2017-09-20 15:59:34 -07:00
parent 2e2b96ef7a
commit 32e823c63e
1 changed files with 15 additions and 0 deletions
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15
drivers/gpu/drm/vc4/vc4_hdmi.c
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@ -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,
};