Peter Robinson reported issues on Fedora with 4k monitors not having
their modes filtered down to 1920x1080 on Raspberry Pi. Hopefully
this resolves that.
Cc: Peter Robinson <pbrobinson@xxxxxxxxxx>
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
---
Note: This is an untested patch, since I'm away from hardware
currently.
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 fa37a1c07cf6..65826a4f208e 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -694,7 +694,22 @@ static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder)
}
}
+static enum drm_mode_status
+vc5_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 = vc5_hdmi_encoder_mode_valid,
.disable = vc4_hdmi_encoder_disable,
.enable = vc4_hdmi_encoder_enable,
};
--
2.14.1
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