drm/vc4: hdmi: Use clk_set_min_rate instead

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.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/821992209cc0d7a83254bf26fe2bf507ef0994d2.1599120059.git-series.maxime@cerno.tech

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 84273fe..487c04d 100644 (file)
--- 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;