From: Hui Fang <hui.fang@nxp.com>
To: Tomasz Figa <tfiga@chromium.org>
Cc: Anle Pan <anle.pan@nxp.com>,
"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
"mchehab@kernel.org" <mchehab@kernel.org>,
"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jindong Yue <jindong.yue@nxp.com>,
Xuegang Liu <xuegang.liu@nxp.com>
Subject: RE: [EXT] Re: [PATCH] media: videobuf2-dma-sg: limit the sg segment size
Date: Tue, 12 Sep 2023 07:01:28 +0000 [thread overview]
Message-ID: <DB9PR04MB92846D75C93A9B2B8C8A998D87F1A@DB9PR04MB9284.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <CAAFQd5Bk0DUq5jgFDHV2wGYEcfQzNVQ2KYJ2ZYLubwFLgqW4kQ@mail.gmail.com>
On Tue, Sep 12 2023 at 11:22 AM Tomasz Figa <tfiga@chromium.org>
> On Mon, Sep 11, 2023 at 3:13 PM Hui Fang <hui.fang@nxp.com> wrote:
> >
> > On Wed, Sep 6, 2023 at 18:28 PM Tomasz Figa <tfiga@chromium.org>
> wrote:
> > > That all makes sense, but it still doesn't answer the real question
> > > on why swiotlb ends up being used. I think you may want to trace
> > > what happens in the DMA mapping ops implementation on your system
> > > causing it to use swiotlb.
> >
> > Add log and feed invalid data to low buffer on purpose, it's confirmed
> > that swiotlb is actually used.
> >
>
> Yes, that we already know. But why?
The physical address of v4l2 buffer is large than 4G (5504139264), so the swiotlb is used.
"[ 846.570271][ T138] software IO TLB: ==== swiotlb_bounce: DMA_TO_DEVICE,
dst 000000004589fa38, src 00000000c6d7e8d8, srcPhy 5504139264, size 4096".
BRs,
Fang Hui
next prev parent reply other threads:[~2023-09-12 7:01 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-28 7:54 [PATCH] media: videobuf2-dma-sg: limit the sg segment size Anle Pan
2023-08-29 10:03 ` Tomasz Figa
2023-08-29 11:14 ` Robin Murphy
2023-08-29 15:04 ` Christoph Hellwig
2023-08-30 3:47 ` Tomasz Figa
2023-08-30 14:33 ` Christoph Hellwig
2023-08-30 16:43 ` Jason Gunthorpe
2023-08-31 12:35 ` Christoph Hellwig
2023-08-31 15:32 ` Jason Gunthorpe
2023-09-01 6:10 ` Christoph Hellwig
2023-09-01 14:26 ` Jason Gunthorpe
[not found] ` <DB9PR04MB92841D8BC1122D5A4210F78987E6A@DB9PR04MB9284.eurprd04.prod.outlook.com>
2023-08-30 13:41 ` [EXT] " Robin Murphy
2023-08-30 3:59 ` Tomasz Figa
2023-09-06 8:52 ` Hans Verkuil
2023-09-06 9:26 ` Tomasz Figa
2023-09-06 9:43 ` Hans Verkuil
2023-08-30 8:50 ` Hui Fang
2023-08-30 9:28 ` Tomasz Figa
2023-09-04 7:10 ` [EXT] " Hui Fang
2023-09-05 3:43 ` Tomasz Figa
2023-09-06 8:16 ` Hui Fang
2023-09-06 9:28 ` Tomasz Figa
2023-09-11 6:13 ` Hui Fang
2023-09-12 2:22 ` Tomasz Figa
2023-09-12 7:01 ` Hui Fang [this message]
2023-09-12 7:10 ` Tomasz Figa
2023-09-12 7:43 ` Hui Fang
2023-09-12 7:51 ` Tomasz Figa
2023-09-13 9:13 ` Hui Fang
2023-09-13 9:44 ` Tomasz Figa
2023-09-13 13:16 ` Hui Fang
2023-09-18 2:28 ` Hui Fang
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