drm/bridge: synopsys: dw-mipi-dsi: Use pixel clock rate to calculate lbcc

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>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230821034008.3876938-6-victor.liu@nxp.com

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index 40d699428b1bdcb15d2fddf850c358fe40ec4193..b21ad4ea9dca3211f2d3e798e645de2f1bf2b4e5 100644 (file)
--- 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/platform_device.h>
@@ -764,8 +765,15 @@ 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;