On 10/1/2022 12:08 PM, Marijn Suijten wrote:
Multiplying a value by 2 and adding 1 to it always results in a value
that is uneven, and that 1 gets truncated immediately when performing
integer division by 2 again. There is no "rounding" possible here.
Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data")
Signed-off-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/msm/dsi/dsi_host.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 8e4bc586c262..e05bae647431 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -1864,12 +1864,7 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
data = 2048 * (dsc->rc_model_size - dsc->initial_offset + num_extra_mux_bits);
dsc->slice_bpg_offset = DIV_ROUND_UP(data, groups_total);
- /* bpp * 16 + 0.5 */
- data = dsc->bits_per_pixel * 16;
- data *= 2;
- data++;
- data /= 2;
- target_bpp_x16 = data;
+ target_bpp_x16 = dsc->bits_per_pixel * 16;
Since this patch is titled, "remove useless math", even the
target_bpp_x16 math looks redundant to me,
first we do
target_bpp_x16 = dsc->bits_per_pixel * 16;
then in the next line we do
data = (dsc->initial_xmit_delay * target_bpp_x16) / 16;
the *16 and /16 will cancel out here.
Instead we can just do
data = (dsc->initial_xmit_delay * dsc->drm->bits_per_pixel) ?
data = (dsc->initial_xmit_delay * target_bpp_x16) / 16;
final_value = dsc->rc_model_size - data + num_extra_mux_bits;
