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

Commit 488f9bc 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 <[email protected]>
raspberrypi · Mar 8, 2017 · 073d94f · 073d94f
1 parent 8196e63
commit 073d94f
Showing 1 changed file with 6 additions and 1 deletion.
diff --git 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,