Re: [PATCH 0/3] media: ipu3-cio2: support concurrent CSI-2 streams

[joe.dzado@icloud.com]

I’ve never submitted a patch before, so I’m not sure if I’m following the right process, but I found something while I was creating a person/gesture detection pipeline on my Surface Laptop (1st generation, 2017) — DMI product_name=Surface Laptop (no "2"+), i5-7200U.

I wanted to use the RGB and IR cameras at the same time and found I could not. So, I got a patch working. 

— Joe


> On Oct 30, 2026, at 6:23 PM, Joe Dzado <joe.dzado@icloud.com> wrote:
> 
> The ipu3-cio2 driver currently assumes a single active capture: every
> stream is pinned to DMA channel 0 (CIO2_DMA_CHAN) and tracked through a
> single cur_queue pointer, with the IRQ handler assuming all completion
> and start-of-frame events belong to that one queue. On platforms with
> more than one sensor wired to separate CSI-2 ports (e.g. the Microsoft
> Surface RGB + IR cameras), starting a second stream reprograms channel 0
> and cur_queue out from under the first, so only one sensor can capture
> at a time.
> 
> This series lets the driver use the DMA channels the hardware actually
> has, so multiple sensors can stream concurrently:
> 
>  1/3 dispatches interrupts by DMA channel instead of a single cur_queue
>      and converts the streaming state to a per-queue count (no
>      functional change);
>  2/3 serialises concurrent hw_init()/hw_exit() with a new lock and
>      guards the block-shared setup so bringing up a second stream does
>      not tear down the first (still single-channel, no functional
>      change);
>  3/3 maps each CSI-2 port to its own DMA channel (2*port), with a
>      dma_per_port module parameter to restore the old behaviour.
> 
> Each patch builds on its own and is bisectable. Tested on a Microsoft
> Surface Laptop (i5-7200U, Kaby Lake) with the OV9734 (colour) and OV7251
> (IR) sensors streaming concurrently on CIO2 ports 1 and 2 for several
> days without errors.
> 
> Joe Dzado (3):
>  media: ipu3-cio2: track the streaming queue by DMA channel
>  media: ipu3-cio2: serialise concurrent stream start and stop
>  media: ipu3-cio2: give each CSI-2 port its own DMA channel
> 
> drivers/media/pci/intel/ipu3/ipu3-cio2.c | 283 ++++++++++++++---------
> drivers/media/pci/intel/ipu3/ipu3-cio2.h |  10 +-
> 2 files changed, 188 insertions(+), 105 deletions(-)
> 
> -- 
> 2.56.0
>