[PATCH] media: uvcvideo: Fix spurious DMA max segment size warnings

From: Takashi Iwai
Date: Thu Jun 09 2022 - 04:22:58 EST


As default, the DMA max segment size is set to 64k, and uvcvideo may
overflow that size easily, resulting in a warning like:

DMA-API: xhci_hcd 0000:00:14.0: mapping sg segment longer than device claims to support [len=98304] [max=65536]

Explicitly set up the DMA max segment size for avoiding spurious kernel
warnings.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
drivers/media/usb/uvc/uvc_video.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 1b4cc934109e..25aa6e6a6906 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -2160,6 +2160,8 @@ int uvc_video_init(struct uvc_streaming *stream)
for_each_uvc_urb(uvc_urb, stream)
INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work);

+ dma_set_max_seg_size(uvc_stream_to_dmadev(stream), UINT_MAX);
+
return 0;
}

--
2.35.3