From 7f98947db09ad419ca73082230ade1f29f18bd82 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Mon, 6 Mar 2017 12:17:16 -0800 Subject: [PATCH 128/454] 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 --- drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- 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 #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,