| Message ID | 20190512184128.13720-2-jagan@amarulasolutions.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/sun4i: sun6i_mipi_dsi: Fixes/updates | expand |
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; }
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 <jagan@amarulasolutions.com> --- drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)