Hi, On Mon, 17 Oct 2022 11:28:57 +0300 Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Dorota, > > Thank you for the patch. > > On Sun, Oct 16, 2022 at 04:39:28PM +0200, Dorota Czaplejewicz wrote: > > Section 13.7.6.13 "CSI Image Parameter Register" of the > > i.MX 8M Quad Applications Processors Reference Manual > > states that the line size should be divisible by 8 bytes. > > However, the hardware also accepts sizes divisible by 4 bytes, > > which are needed to fully utilize the S5K3L6XX sensors. > > > > This patch accepts line sizes divisible by 4 bytes. > > The patch itself looks fine, but I always worry when we depart from the > documentation (sometimes that's a worry about documentation inaccuracies > :-)). In this particular case, we need to test the change on i.MX7 too, > as the alignment constraints could be platform-specific. > I don't have access to any i.MX7 hardware, unfortunately. I can help anyone who does and wants to test this. > I would also very much appreciate feedback from NXP on this. There's a > risk of ill side-effects that I would prefer ruling out very clearly. I posted a question on the NXP forum: https://community.nxp.com/t5/i-MX-Processors/i-MX8MQ-CSI-line-size-constraint-documentation-mistake/m-p/1538629#M196448 --Dorota > > > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@xxxxxxx> > > --- > > Hello, > > > > the Librem 5 is using an out-of-tree driver for s5k3l6xx, and rounding to 4 is optimal to operate it. > > > > This revision improves the commit message. > > > > Cheers, > > Dorota Czaplejewicz > > > > drivers/staging/media/imx/imx7-media-csi.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/staging/media/imx/imx7-media-csi.c b/drivers/staging/media/imx/imx7-media-csi.c > > index a0553c24cce4..af821b410c3f 100644 > > --- a/drivers/staging/media/imx/imx7-media-csi.c > > +++ b/drivers/staging/media/imx/imx7-media-csi.c > > @@ -999,10 +999,10 @@ static int imx7_csi_mbus_fmt_to_pix_fmt(struct v4l2_pix_format *pix, > > } > > > > /* Round up width for minimum burst size */ > > - width = round_up(mbus->width, 8); > > + width = round_up(mbus->width, 4); > > > > /* Round up stride for IDMAC line start address alignment */ > > - stride = round_up((width * cc->bpp) >> 3, 8); > > + stride = round_up((width * cc->bpp) >> 3, 4); > > > > pix->width = width; > > pix->height = mbus->height; >
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