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

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Message-Id: <20220609082246.13182-1-tiwai@suse.de>
Date:   Thu,  9 Jun 2022 10:22:46 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] media: uvcvideo: Fix spurious DMA max segment size warnings

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@...e.de>
---
 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