[PATCH v5 64/80] drm/vc4: hdmi: Use clk_set_min_rate instead

Maxime Ripard maxime at cerno.tech
Thu Sep 3 04:01:36 EDT 2020


The HSM clock needs to be running at 101% the pixel clock of the HDMI
controller, however it's shared between the two HDMI controllers, which
means that if the resolutions are different between the two HDMI
controllers, and the lowest resolution is on the second (in enable order)
controller, the first HDMI controller will end up with a smaller than
expected clock rate.

Since we don't really need an exact frequency there, we can simply change
the minimum rate we expect instead.

Reviewed-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
Tested-by: Chanwoo Choi <cw00.choi at samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon at samsung.com>
Tested-by: Stefan Wahren <stefan.wahren at i2se.com>
Signed-off-by: Maxime Ripard <maxime at cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 84273fe650d6..487c04de6b85 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -462,7 +462,7 @@ static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder)
 	 * pixel clock, but HSM ends up being the limiting factor.
 	 */
 	hsm_rate = max_t(unsigned long, 120000000, (pixel_rate / 100) * 101);
-	ret = clk_set_rate(vc4_hdmi->hsm_clock, hsm_rate);
+	ret = clk_set_min_rate(vc4_hdmi->hsm_clock, hsm_rate);
 	if (ret) {
 		DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
 		return;
-- 
git-series 0.9.1



More information about the linux-arm-kernel mailing list