[PATCH 5/9] drm/bridge: synopsys: dw-mipi-dsi: Use pixel clock rate to calculate lbcc

Liu Ying
2023-07-17T06:14:23Z

To get better accuration, use pixel clock rate to calculate lbcc instead of
lane_mbps since the pixel clock rate is in KHz while lane_mbps is in MHz.
Without this, distorted image can be seen on a HDMI monitor connected with
i.MX93 11x11 EVK through ADV7535 DSI to HDMI bridge in 1920x1080p@60 video
mode.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
---
drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index c754d55f71d1..332388fd86da 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -12,6 +12,7 @@
#include <linux/component.h>
#include <linux/debugfs.h>
#include <linux/iopoll.h>
+#include <linux/math64.h>
#include <linux/media-bus-format.h>
#include <linux/module.h>
#include <linux/of_device.h>
@@ -762,8 +763,15 @@ static u32 dw_mipi_dsi_get_hcomponent_lbcc(struct dw_mipi_dsi *dsi,
u32 hcomponent)
{
u32 frac, lbcc;
+ int bpp;

- lbcc = hcomponent * dsi->lane_mbps * MSEC_PER_SEC / 8;
+ bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+ if (bpp < 0) {
+ dev_err(dsi->dev, "failed to get bpp\n");
+ return 0;
+ }
+
+ lbcc = div_u64((u64)hcomponent * mode->clock * bpp, dsi->lanes * 8);

frac = lbcc % mode->clock;
lbcc = lbcc / mode->clock;
--
2.37.1