drm/msm/dsi: improve/fix dsc pclk calculation

flto · Abhinav Kumar · commit 24436a540d16 · 2024-10-14T13:16:17.000-07:00
drm_mode_vrefresh() can introduce a large rounding error, avoid it. Fixes: 7c9e4a5 ("drm/msm/dsi: Reduce pclk rate for compression") Signed-off-by: Jonathan Marek <jonathan@marek.ca> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com> Patchwork: https://patchwork.freedesktop.org/patch/618432/ Link: https://lore.kernel.org/r/20241007050157.26855-1-jonathan@marek.ca Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -542,7 +542,7 @@ static unsigned long dsi_adjust_pclk_for_compression(const struct drm_display_mo
 
 	int new_htotal = mode->htotal - mode->hdisplay + new_hdisplay;
 
-	return new_htotal * mode->vtotal * drm_mode_vrefresh(mode);
+	return mult_frac(mode->clock * 1000u, new_htotal, mode->htotal);
 }
 
 static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode,

Original file line number	Diff line number	Diff line change
`@@ -542,7 +542,7 @@ static unsigned long dsi_adjust_pclk_for_compression(const struct drm_display_mo`
`542`	`542`
`543`	`543`	`int new_htotal = mode->htotal - mode->hdisplay + new_hdisplay;`
`544`	`544`
`545`		`- return new_htotal * mode->vtotal * drm_mode_vrefresh(mode);`
	`545`	`+ return mult_frac(mode->clock * 1000u, new_htotal, mode->htotal);`
`546`	`546`	`}`
`547`	`547`
`548`	`548`	`static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode,`