On Mon Mar 23 16:33:31 2026 +0800, Guoniu Zhou wrote:
> The ISI hardware rounds the actual output size up to an integer, as
> described in i.MX93 Reference Manual section 57.7.8 (Channel 0 Scale
> Factor). The scale factor must be calculated to ensure the theoretical
> output value rounds up to exactly the desired size.
>
> Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
> Cc: [email protected]
> Signed-off-by: Guoniu Zhou <[email protected]>
> Reviewed-by: Laurent Pinchart <[email protected]>
> Link: https://patch.msgid.link/[email protected]
> Signed-off-by: Laurent Pinchart <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
index 0187d4ab97e8..16b20ea2d1db 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
@@ -112,7 +112,14 @@ static u32 mxc_isi_channel_scaling_ratio(unsigned int
from, unsigned int to,
else
*dec = 8;
- return min_t(u32, from * 0x1000 / (to * *dec), ISI_DOWNSCALE_THRESHOLD);
+ /*
+ * The ISI rounds output dimensions up to the next integer (i.MX93 RM
+ * section 57.7.8). Calculate the scale factor such that the theoretical
+ * output (input / scale_factor) rounds up to exactly the desired
+ * output.
+ */
+ return min_t(u32, DIV_ROUND_UP(from * 0x1000, to * *dec),
+ ISI_DOWNSCALE_THRESHOLD);
}
static void mxc_isi_channel_set_scaling(struct mxc_isi_pipe *pipe,
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