From 51a0d1a90bff5d90a1a1c58e165928a0dd92268a Mon Sep 17 00:00:00 2001 From: Jagan Teki Date: Mon, 13 May 2019 00:11:26 +0530 Subject: [PATCH] drm/sun4i: sun6i_mipi_dsi: Fix hsync_porch overflow Loop N1 instruction delay for burst mode devices are computed based on horizontal sync and porch timing values. The current driver is using u16 type for computing this hsync_porch value, which would failed to fit within the u16 type for large sync and porch timings devices. This would result in hsync_porch overflow and eventually computed wrong instruction delay value. Example, timings, where it produces the overflow { .hdisplay = 1080, .hsync_start = 1080 + 408, .hsync_end = 1080 + 408 + 4, .htotal = 1080 + 408 + 4 + 38, } It reproduces the desired delay value 65487 but the correct working value should be 7. So, Fix it by computing hsync_porch value separately with u32 type. Fixes: 1c1a7aa3663c ("drm/sun4i: dsi: Add burst support") Signed-off-by: Jagan Teki Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20190512184128.13720-2-jagan@amarulasolutions.com --- drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index 6ff585055a07..bfa7e2b146df 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -457,8 +457,9 @@ static void sun6i_dsi_setup_inst_loop(struct sun6i_dsi *dsi, u16 delay = 50 - 1; if (device->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) { - delay = (mode->htotal - mode->hdisplay) * 150; - delay /= (mode->clock / 1000) * 8; + u32 hsync_porch = (mode->htotal - mode->hdisplay) * 150; + + delay = (hsync_porch / ((mode->clock / 1000) * 8)); delay -= 50; } -- 2.30.2