Re: [PATCH v2 00/17] Rework frame descriptors

Hi,

On 14/08/2026 11:17, Mattijs Korpershoek wrote:
> Hi Sakari,
> 
> Thank you for the series.
> 
> On Mon, May 18, 2026 at 19:43, Sakari Ailus <[email protected]> wrote:
> 
>> Hi folks,
>>
>> This smallish set makes frame descriptors dynamically allocated and
>> implements a single-entry frame descriptor based on the device's format,
>> using a new helper called v4l2_subdev_get_frame_desc(). All drivers that
>> do not obtain their frame descriptor from upstream are converted. The
>> helper also obtains a frame descriptor for the desired type (parallel or
>> CSI-2) and checks there's at least one entry there. These checks are
>> removed from drivers that currently perform them. (Some drivers also check
>> there's exactly a single frame descriptor entry but I think in most cases
>> this check could be loosened. That could be done after this set.)
>>
>> On callee side these patches introduce no changes as the number of
>> pre-allocated memory for 8 frame descriptors remains as-is. The
>> get_frame_desc() pad op can return more than 8 frame descriptors by
>> setting the num_entries to the desired number and returning -ENOSPC.
>>
>> If people prefer using cleanup.h / __free() to release the dynamically
>> allocated array (I think I'd almost require that), I'll merge the
>> now-separate __v4l2_subdev_get_frame_desc() into
>> v4l2_subdev_get_frame_desc().
>>
>> More formats can be added to df-to-mbus conversion as needed. These are
>> meant to be initial formats that are enough for typical raw sensors (and
>> one RGB format, too).
> 
> I've tried this out on a AM69-SK with the Arducam FPD V3Link[1] using
> the following device tree overlays:
>    ti/k3-am68-sk-v3link-fusion.dtbo ti/k3-v3link-imx219-0-0.dtbo
> 
> See TI's documentation about this [2]
> 
> I (naively) assumed that this series would replace Tomi's patch [3], but
> it did not. I see the following in dmesg:
> 
> [  286.686574] cdns-csi2rx 4504000.csi-bridge: collect_streams: "cdns_csi2rx.4504000.csi-bridge":1: found 0x1 enabled 0x0
> [  286.686754] ds90ub953 7-0044: Failed to get frame desc from remote subdev imx219 10-0010
> [  286.700147] ds90ub960 7-0030: Failed to get source frame desc for pad 0
> [  286.712679] j721e-csi2rx 4500000.ticsi2rx: enable streams "ds90ub960 7-0030":4/0x1
> [  286.712684] ds90ub960 7-0030: collect_streams: "ds90ub960 7-0030":4: found 0x1 enabled 0x0
> [  286.712690] ds90ub953 7-0044: Failed to get frame desc from remote subdev imx219 10-0010
> [  286.725884] j721e-csi2rx 4500000.ticsi2rx: enable streams 4:0x1 failed: -515
> 
> Here is my camera topology:
> https://paste.debian.net/hidden/7f56f635
> 
> I also made the following patch to attempt to convert over j721e-csi2rx:
> https://paste.debian.net/hidden/314f9c32
> 
> Is this series indeed aimed to replace all sensor-specific
> implementations of .get_frame_desc() or are patches such as the one send
> from Tomi [3] still useful?
I don't remember the details anymore, but probably related to my comment 
in this thread:

"It also looks like you only modified platform drivers. Did you check 
the i2c drivers? Some call get_frame_desc().". So I think ub953 is 
missing the conversion to v4l2_subdev_get_frame_desc().

  Tomi