drm/msm/dsi: fix 32-bit signed integer extension in pclk_rate calculation

When (mode->clock * 1000) is larger than (1<<31), int to unsigned long
conversion will sign extend the int to 64 bits and the pclk_rate value
will be incorrect.

Fix this by making the result of the multiplication unsigned.

Note that above (1<<32) would still be broken and require more changes, but
its unlikely anyone will need that anytime soon.

Fixes: c4d8cfe516dc ("drm/msm/dsi: add implementation for helper functions")
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/618434/
Link: https://lore.kernel.org/r/20241007050157.26855-2-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
index 1205aa3..a98d24b 100644 (file)
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -550,7 +550,7 @@ static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode,
 {
        unsigned long pclk_rate;
 
-       pclk_rate = mode->clock * 1000;
+       pclk_rate = mode->clock * 1000u;
 
        if (dsc)
                pclk_rate = dsi_adjust_pclk_for_compression(mode, dsc);