Re: [PATCH v15 00/22] media: i2c: add Maxim GMSL2/3 serializer and deserializer drivers

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hei Tomi,

On Wed, Aug 26, 2026 at 01:15:03PM +0300, Tomi Valkeinen wrote:
> Hi,
> 
> On 07/08/2026 16:02, Dumitru Ceclan via B4 Relay wrote:
> > This series adds new drivers for multiple Maxim GMSL2 and GMSL3 devices,
> > replacing the few GMSL2 drivers already in upstream, and introducing a
> > common framework that can be used to implement such GMSL chips, which
> > avoids code duplication while also adding support for previously
> > unsupported features.
> If you send a series, it needs your Signed-off-by.

Thanks for testing this. It's been out for review for long but without much
attention. :-\

> 
> This series also depends on the internal pad, which is not upstream and is
> not just a straightforward add-a-define case. Sakari's "[PATCH v12 00/86]
> Generic line based metadata support, internal pads" has it, and additional
> patches around it. For the time being, I think the internal pad
> unfortunately blocks merging this.

I've briefly discussed this with Laurent and it seems we both think the
internal pads could be introduced for this purpose. I don't see this being
an issue; we still need to pay attention to how they are used which we'd
need to do in any case.

> 
> However, (correct me if I'm wrong) the internal pad is only required for
> TPG. An option would be to remove the TPG support (or at least the parts
> that make it visible, i.e. you could keep the internal functionality), thus
> removing the blocker. The TPG could be added later on top.

That's an option, yes, but I'd just merge the internal pad patch.

> 
> I tested the series on Xilinx Kria KV260 and on TI AM62A SK, both with
> max96716 deserializer and two max96717 serializers with imx219. On Xilinx I
> used RAW8, with and without embedded data. On AM62A I used RAW8 and RAW10.
> 
> The deserializer TPG gives me no frames at all. I recall the clocking for
> the TPG was quite a challenge on at least some max96 serializers, so maybe
> it's related to that.
> 
> The serializer TPG worked, although I think there's something funny with it:
> the initial frames (maybe just the first one) seem to be truncated a bit,
> there's black at the bottom. Another, a bit more unclear, is that sometimes
> ser tpg stops working. If I'm not mistaken, what I did was run cam0-tpg +
> cam1-tpg. Then I tried des tpg. Then cam0-tpg, but it gives me nothing.
> Streaming with cam0+cam1 video "resets" things and it all works again. I've
> seen this a few times, but there seems to be some randomness so I haven't
> been able to pinpoint it, but feels like there's some extra state that's
> left behind into the HW.
> 
> All in all, the normal case (non-tpg) works ok for me:

I'd indeed either fix the TPG before merging the set or postpone adding it
for this reason. :-)

> 
> Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

-- 
Terveisin,

Sakari Ailus