[PATCH v3] media: rkisp1: Remove min_queued_buffers

[Hans Verkuil]

On 2/20/25 15:22, Jacopo Mondi wrote:
> Hello
> 
> On Tue, Oct 29, 2024 at 09:21:16AM +0100, Jacopo Mondi wrote:
>> There apparently is no reason to require 3 queued buffers for RkISP1,
>> as the driver operates with a scratch buffer where data can be
>> directed to if there's no available buffer provided by userspace.
>>
>> Reduce the number of required buffers to 0 by removing the
>> initialization of min_queued_buffers, to allow applications to operate
>> by queueing capture buffers on-demand.
>>
>> Tested with libcamera, by operating with a single capture request. The
>> same request (and the associated capture buffer) gets recycled once
>> completed. This of course causes a frame rate drop but doesn't hinder
>> operations.
>>
>> Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> 
> I just noticed v2 of this series:
> media: rkisp1: Reduce min_queued_buffers to 1
> 
> has been collected instead of this v3.

Did you mark your v2 as Superseded in patchwork when you posted the v3?
I marked your v1 and v2 as Superseded today when I was cleaning up patchwork,
so I know you didn't :-)

When I post a new version I always mark the old one as Superseded, exactly
to prevent such things from happening.

Also, more people should help keep patchwork clean. I think I am usually the
person who is doing this, but this is a collective responsibility.

Part of the job description for someone with commit rights is actually to
keep patchwork clean.

Regards,

	Hans

> 
> And I noticed because a user complained to me about this.
> 
> Now, I can provide an update based on the now merged v2, not a big
> deal, but this depresses me a bit as the discussion about
> implementing multi-commiter model is apparently (again) stalled.
> 
> I know, sh*t happens (TM) and hiccups are expected in the process,
> we all make mistakes and I'm not even sure through which path the
> patch has been collected, but I could have handled this one easily,
> and instead what we have is:
> 
> 1) an unhappy user that will likely have to wait for the next release
> 2) me having to send an additional (rather trivial) patch
> 3) Someone will have to review, collect, PR etc etc
> 
> (and I'm not even mentioning this patch is 3 lines)
> 
> Issues like this one seems to be considered a fact of life we decided
> is fine to live with, while every possible corner case of the proposed
> multi-committer model is analyzed with great concern like we're
> trading a perfect model for something that has to be equally perfect.
> 
> And while I agree the biggest reason for the proverbial v4l2 slow pace
> is the reviewers scarcity and the limited maintainers bandwidth, now
> that we have everything in place to reduce the system clogginess
> it still seems we're not all sold for it. I really don't get it, sorry.
> 
> 
>> ---
>> v2->v3:
>> - Remove min_queued_buffers initialization
>>
>> v1->v2:
>> The first version of this patch set min_queued_buffers to 1, but setting it
>> to 0 doesn't compromise operations and it's even better as it allows application
>> to queue buffers to the capture devices on-demand. If a buffer is not provided
>> to the DMA engines, image data gets directed to the driver's internal scratch
>> buffer.
>> ---
>>  drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> index 2bddb4fa8a5c..2f0c610e74b9 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> @@ -35,8 +35,6 @@
>>  #define RKISP1_SP_DEV_NAME	RKISP1_DRIVER_NAME "_selfpath"
>>  #define RKISP1_MP_DEV_NAME	RKISP1_DRIVER_NAME "_mainpath"
>>
>> -#define RKISP1_MIN_BUFFERS_NEEDED 3
>> -
>>  enum rkisp1_plane {
>>  	RKISP1_PLANE_Y	= 0,
>>  	RKISP1_PLANE_CB	= 1,
>> @@ -1563,7 +1561,6 @@ static int rkisp1_register_capture(struct rkisp1_capture *cap)
>>  	q->ops = &rkisp1_vb2_ops;
>>  	q->mem_ops = &vb2_dma_contig_memops;
>>  	q->buf_struct_size = sizeof(struct rkisp1_buffer);
>> -	q->min_queued_buffers = RKISP1_MIN_BUFFERS_NEEDED;
>>  	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>>  	q->lock = &node->vlock;
>>  	q->dev = cap->rkisp1->dev;
>> --
>> 2.47.0
>>
>>