On Wed, Mar 23, 2022 at 10:50:19AM +0100, Jacopo Mondi wrote: > Hi Tomi thanks for testing > > On Wed, Mar 23, 2022 at 10:51:04AM +0200, Tomi Valkeinen wrote: > > Hi Jacopo, > > > > On 24/02/2022 11:42, Jacopo Mondi wrote: > > > v1: > > > https://patchwork.linuxtv.org/project/linux-media/list/?series=7249 > > > v2: > > > https://patchwork.linuxtv.org/project/linux-media/list/?series=7311 > > > v3: > > > https://patchwork.linuxtv.org/project/linux-media/list/?series=7385 > > > v4: > > > https://patchwork.linuxtv.org/project/linux-media/list/?series=7389 > > > > > > A branch for testing based on the most recent media-master is available at > > > https://git.sr.ht/~jmondi_/linux #jmondi/media-master/ov5640-v5 > > > > I tested these with DRA76 EVM & CAL, using CAL's legacy non-MC mode. It > > doesn't work. I think there are two problems: > > > > - CAL uses mbus codes like MEDIA_BUS_FMT_UYVY8_2X8 for CSI-2, not 1X16. > > OV5640 used to support 2X8, but now it doesn't. > > > > - OV5640 sets the default code to MEDIA_BUS_FMT_UYVY8_2X8, even for CSI-2 > > where it doesn't support MEDIA_BUS_FMT_UYVY8_2X8. > > This might be worth an additional patch that decides what default > format to use based on the bus type. > > > I'd like to just change CAL and drop the 2X8 support and instead use 1X16, > > but then any sensor that uses 2X8 would work. So I guess I need to change > > the code to support both. > > > > Anyway, both of those issues might also surface on other platforms, as > > ov5640 behavior has changed. > > I'm afraid sooner or later this should have happened ? > > I think CSI-2 receivers should be updated, but I share your concerns > about breaking other platforms. > > On one side we shouldn't be breaking userspace and this change might > break some assumptions in users' pipeline configuration scripts and > could prevent drivers that used to work together from being > compatible at all. > > On the other side we would never be able to change anything at all if > such a change is expected to happen atomically on all platforms and > sensors. > > As the change is so trivial I guess it's fair to expect users of > bridge drivers not compatible with 1X16 to fix them, but I cannot tell > if it's an acceptable policy or not. > > As Sakari suggested we could also move all CSI-2 transmitters to use 1X16 > and have receivers adjust as soon as someone detects a breakage. > > I can revert the change that restricts the enumerated format to the > currently in use bus type[1] if desired, but I would prefer receivers > to adjust when needed. Is this acceptable ? That would be my preference too. How about implementing Sakari's suggestion of turning the 2X8 formats into 1X16 in .set_fmt() for CSI-2 ? That way we'll minimize any risk of breakage for userspace. Host-side drivers that use the OV5640 will still need to be converted from 2X8 to 1X16, but that's in-kernel only and should be manageable. > [1] "media: ov5640: Split DVP and CSI-2 formats -- Regards, Laurent Pinchart
