Re: [PATCH] media: ti: j721e-csi2rx: Allow passing cache hints from user-space

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Devarsh,

Thanks for the patch.

On Wed, Mar 12, 2025 at 04:51:40PM +0530, Devarsh Thakkar wrote:
> User-space can provide cache hints to enable software managed cache
> operations or skip certain cache operations using memory flags
> and buffer flags. This is useful for SoCs such as AM62px
> which do not support hardware cache coherency.
> 
> This is tested on AM62px with yavta capture by passing
> V4L2_MEMORY_FLAG_NON_COHERENT while using VIDIOC_REQBUFS
> and V4L2_BUF_FLAG_NO_CACHE_CLEAN while using VIDIOC_QBUF
> and ~5x reduction in memcpy time is seen for
> copying captured frame to DDR as shared here [1].

The lines may be up to 75 characters long here. Most editors can handle the
wrapping for you, I've rewrapped the text in this case and edited it a
little, as Jai suggested.

> 
> [1]:
> Link: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1452545/am62p-the-ads6311-radar-camera-has-lost-frame-capture/5580472#5580472
> Signed-off-by: Devarsh Thakkar <devarsht@ti.com>
> ---
>  drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> index 6412a00be8ea..284d33b2a0ec 100644
> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -895,6 +895,7 @@ static int ti_csi2rx_init_vb2q(struct ti_csi2rx_dev *csi)
>  	q->dev = dmaengine_get_dma_device(csi->dma.chan);
>  	q->lock = &csi->mutex;
>  	q->min_queued_buffers = 1;
> +	q->allow_cache_hints = 1;
>  
>  	ret = vb2_queue_init(q);
>  	if (ret)

-- 
Regards,

Sakari Ailus