Re: [PATCH 5/8] media: qcom: camss: vfe: only reset the VFE when its last line stops

[Bryan O'Donoghue <bryan.odonoghue@linaro.org>]

On 14/09/2026 14:34, Hitesh Patel wrote:
> vfe_disable_output() stops the write masters of the line being
> disabled and then issues a global VFE reset. The reset is not scoped
> to the line: it resets the whole block.
> 
> Several lines of one VFE stream at the same time when a CSID
> demultiplexes virtual channels to different RDIs, e.g. two GMSL
> cameras aggregated by a MAX9296A onto one CSI-2 port, each on its

You can drop references to a particular part - all aggregators would do 
this.

> own VC and RDI. Stopping one of them then resets the VFE underneath
> the other: its in-flight buffers are never completed, its write
> master configuration is gone and the block is left in a state where
> the next reset is not acknowledged, which surfaces as

"Stopping one of the streams/VFEs/RDIs" - basically we haven't defined 
what the "it" in this paragraph is "its write master configuration is gone"

What it ? Define the object instead of assuming the reader knows what is 
meant by it.

IT: a spider that lives in the sewers of Derry Maine.. [1]

>    VFE reset timeout
> 
> when the remaining camera is stopped or restarted.
> 
> Only issue the reset when the line being disabled is the last one
> streaming on this VFE, as tracked by vfe->stream_count. Stopping the
> line's write masters is sufficient to quiesce it while other lines
> keep running. The single-line case resets exactly as before.
> 
> Signed-off-by: Hitesh Patel <hitesh@ebytelogic.com>
> ---
>   drivers/media/platform/qcom/camss/camss-vfe.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss-vfe.c b/drivers/media/platform/qcom/camss/camss-vfe.c
> index 319d19158..9cdf26671 100644
> --- a/drivers/media/platform/qcom/camss/camss-vfe.c
> +++ b/drivers/media/platform/qcom/camss/camss-vfe.c
> @@ -814,6 +814,7 @@ static int vfe_disable_output(struct vfe_line *line)
>   	struct vfe_output *output = &line->output;
>   	unsigned long flags;
>   	unsigned int i;
> +	bool last;
>   
>   	spin_lock_irqsave(&vfe->output_lock, flags);
>   	for (i = 0; i < output->wm_num; i++)
> @@ -821,6 +822,13 @@ static int vfe_disable_output(struct vfe_line *line)
>   	output->gen2.active_num = 0;
>   	spin_unlock_irqrestore(&vfe->output_lock, flags);
>   
> +	mutex_lock(&vfe->stream_lock);
> +	last = vfe->stream_count == 1;
> +	mutex_unlock(&vfe->stream_lock);
> +
> +	if (!last)
> +		return 0;
> +
>   	return vfe_reset(vfe);
>   }
>   

Other than the rambling commit log - looks like a valid Fix to me.

Again

- Fixes tag
- Fixes to first
- Fix in the patch title name

[1] We all float down here.