Hi Dorota, On Wed, 2021-10-13 at 11:26 +0200, Dorota Czaplejewicz wrote: > On Fri, 08 Oct 2021 14:19:41 +0200 Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote: [...] > > I wonder: if you use 4-byte aligned width and odd height, does the CSI > > write over the end of the buffer? > > I tested this case, and found a glitch which suggests the last 4 bytes are ignored: > > https://source.puri.sm/Librem5/linux-next/uploads/cfb59e3832431aaa3a69549455502568/image.png Thank you for testing, so it appears that at least without FBUF_STRIDE the only requirement is that the whole image size must be a multiple of 8 bytes. > That would be taken care of rounding up towards a number decided at runtime, like: > > divisor = 8 >> (mbus->height % 2); Which would then cause the CSI to write past the end of the buffer? I'd rather make sure that either the number of lines is even or the width is a multiple of 8 bytes. > > > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@xxxxxxx> > > > --- > > > > > > Hello, > > > > > > my previous patch identified something that was not a problem, > > > so I'm sending a different one. > > > > > > This has been tested on the Librem 5. > > > > > > Cheers, > > > Dorota > > > > > > drivers/staging/media/imx/imx-media-utils.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/staging/media/imx/imx-media-utils.c b/drivers/staging/media/imx/imx-media-utils.c > > > index 5128915a5d6f..a303003929e3 100644 > > > --- a/drivers/staging/media/imx/imx-media-utils.c > > > +++ b/drivers/staging/media/imx/imx-media-utils.c > > > @@ -545,13 +545,13 @@ int imx_media_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 */ > > > if (cc->planar) > > > stride = round_up(width, 16); > > > else > > > - stride = round_up((width * cc->bpp) >> 3, 8); > > > + stride = round_up((width * cc->bpp) >> 3, 4); > > > > Second, even if this works fine on the i.MX7/8M CSI, the alignment is > > still required for the i.MX5/6 IPU, for which this code and the comments > > were written. So we need a way to differentiate the two cases here. > > > > regards > > Philipp > > How best to go about this? I can see in the file imx-media-capture.c > that there the video device lives in struct capture_priv.vdev.vfd. > Would that be the right place to query about the underlying hardware? > > Then the following functions would gain a new "small_divisor" parameter: > - imx_media_mbus_fmt_to_pix_fmt (a GPL symbol) > - imx_media_mbus_fmt_to_ipu_image (a GPL symbol) > - __capture_try_fmt That sounds like it would work around the current code when it (at least part of imx_media_mbus_fmt_to_pix_fmt()) should be split between i.MX5/6 and i.MX7/8 implementations. For example rounding up the stride is not useful on i.MX7/8, it just doesn't currently hurt because imx7-media-csi is not using bytesperline to set up FBUF_STRIDE. And certainly the comments don't apply. imx_media_mbus_fmt_to_ipu_image() is unused and should probably be dropped, same as imx_media_ipu_image_to_mbus_fmt(). > Those would have to extract the device type from struct capture_priv: > - __capture_legacy_try_fmt > - capture_try_fmt_vid_cap > - capture_s_fmt_vid_cap > - capture_init_format Maybe imx_media_mbus_fmt_to_pix_fmt should be moved into imx-media- capture.c be passed struct capture_priv to avoid duplicating the device type check? imx_media_capture_device_init() could gain a new parameter (or maybe replace legacy_api) to set the device type. regards Philipp
