linux-kernel - Re: [PATCH v7 11/16] media: ti: j721e-csi2rx: add multistream support

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Message-ID: <175983794202.36451.17500767517117494893@freya>
Date: Tue, 07 Oct 2025 17:22:22 +0530
From: Jai Luthra <jai.luthra@...asonboard.com>
To: Rishikesh Donadkar <r-donadkar@...com>, Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, jai.luthra@...ux.dev, laurent.pinchart@...asonboard.com, mripard@...nel.org
Cc: y-abhilashchandra@...com, devarsht@...com, s-jain1@...com, vigneshr@...com, mchehab@...nel.org, robh@...nel.org, krzk+dt@...nel.org, p.zabel@...gutronix.de, conor+dt@...nel.org, sakari.ailus@...ux.intel.com, hverkuil-cisco@...all.nl, changhuang.liang@...rfivetech.com, jack.zhu@...rfivetech.com, sjoerd@...labora.com, hverkuil+cisco@...nel.org, linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v7 11/16] media: ti: j721e-csi2rx: add multistream support

Hi Tomi,

Quoting Tomi Valkeinen (2025-09-25 17:47:38)
> Hi,
> 
> On 11/09/2025 13:28, Rishikesh Donadkar wrote:
> > From: Jai Luthra <j-luthra@...com>
> > 
> > Each CSI2 stream can be multiplexed into 4 independent streams, each
> > identified by its virtual channel number. To capture this multiplexed
> 
> The split can also be done with the datatype. I don't see it supported
> in the driver, but afaics the HW supports it. Was there a reason not to
> support DT filtering? I would think it would be very simple addition.
> 

I believe DT filtering should work as-is with the current driver, given we
program the SHIM DMACNTX register with the correct datatype depending upon
the v4l2 format of the video node.

So if there is multi-stream source with two different datatypes, it should
be possible to route it to different video devices and it "just" works. But
I agree that it would be good if it can be tested once, and this commit
message can mention that both VC and DT based filtering is supported.

Rishikesh, would you be able to use an IMX219 to test capturing embedded
data and frame data?

>  Tomi
> 

Thanks,
    Jai

> > stream, the application needs to tell the driver how it wants to route
> > the data. It needs to specify which context should process which stream.
> > This is done via the new routing APIs.
> > 
> > Add ioctls to accept routing information from the application and save
> > that in the driver. This can be used when starting streaming on a
> > context to determine which route and consequently which virtual channel
> > it should process.
> > 
> > Support the new enable_stream()/disable_stream() APIs in the subdev
> > instead of s_stream() hook.
> > 
> > De-assert the pixel interface reset on first start_streaming() and assert
> > it on the last stop_streaming().
> > 
> > Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@...com>
> > Co-developed-by: Pratyush Yadav <p.yadav@...com>
> > Signed-off-by: Pratyush Yadav <p.yadav@...com>
> > Signed-off-by: Jai Luthra <j-luthra@...com>
> > Co-developed-by: Rishikesh Donadkar <r-donadkar@...com>
> > Signed-off-by: Rishikesh Donadkar <r-donadkar@...com>

[snip]