panel-raspberrypi-touchscreen: Round up clk rate to fix DSI panel.

Commit 488f9bc8e3def93e0baef53cee2026c2cb0d8956 slightly increased the
reported rate of PLLD, so the clk driver decided that PLLD/3/8 was now
higher than our requested pixel clock rate and rejected it in favor of
PLLD/4/8, which then ran the pixel clock way out of spec.

By bumping the requested clock rate just slightly, we get back to
PLLD/3/8 like we wanted and the panel displays content again.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 1a536fe4d040f5fafe324baee110a6225dd0be08..7f315f04b109621ca7f3861fdd8acf956e752629 100644 (file)
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -220,7 +220,12 @@ static const struct drm_display_mode rpi_touchscreen_modes[] = {
 #define HBP         46
 #define HFP         ((PIXEL_CLOCK / (VTOTAL * VREFRESH)) - (HACT + HSW + HBP))
 
-               .clock = PIXEL_CLOCK / 1000,
+               /* Round up the pixel clock a bit (10khz), so that the
+                * "don't run things faster than the requested clock
+                * rate" rule of the clk driver doesn't reject the
+                * divide-by-3 mode due to rounding error.
+                */
+               .clock = PIXEL_CLOCK / 1000 + 10,
                .hdisplay = HACT,
                .hsync_start = HACT + HFP,
                .hsync_end = HACT + HFP + HSW,