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From: Jie Deng <jie.deng@intel.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Jason Wang" <jasowang@redhat.com>,
	"Linux I2C" <linux-i2c@vger.kernel.org>,
	virtualization@lists.linux-foundation.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Wolfram Sang" <wsa@kernel.org>,
	"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	conghui.chen@intel.com, kblaiech@mellanox.com,
	jarkko.nikula@linux.intel.com,
	"Sergey Semin" <Sergey.Semin@baikalelectronics.ru>,
	"Mike Rapoport" <rppt@kernel.org>,
	loic.poulain@linaro.org, "Tali Perry" <tali.perry1@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	yu1.wang@intel.com, shuo.a.liu@intel.com,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [PATCH v7] i2c: virtio: add a virtio i2c frontend driver
Date: Tue, 16 Mar 2021 10:15:48 +0800	[thread overview]
Message-ID: <770332a7-f34d-fe26-f708-830b587a98d5@intel.com> (raw)
In-Reply-To: <CAK8P3a0LjcSs7gvU-jRdZJCFrfxQcSUWqL_fgH_71VjC027M0w@mail.gmail.com>


On 2021/3/15 15:52, Arnd Bergmann wrote:
> On Mon, Mar 15, 2021 at 6:54 AM Jie Deng <jie.deng@intel.com> wrote:
>> On 2021/3/15 11:13, Jason Wang wrote:
>>> On 2021/3/15 9:14 上午, Jie Deng wrote:
>>>> On 2021/3/12 16:58, Arnd Bergmann wrote:
>> Then do you think it is necessary to mark the virtio bufs with
>> ____cacheline_aligned ?
> I think so, yes.
>
>> I haven't seen any virtio interface being marked yet. If this is a
>> problem, I believe it should  be common for all virtio devices, right ?
> Yes, but it's not a problem if the buffers are allocated separately
> because kmalloc provinces a cachelinen aligned buffer on architectures
> that need it.
>
> It's only a problem here because there is a single allocation for three
> objects that have different ownership states during the DMA (device
> owned to-device, cpu-owned, device owned to-cpu).
>
>         Arnd
I'm not sure if this will actually cause a problem. But I'm OK to mark 
the items
in struct virtio_i2c_req with  ____cacheline_aligned to avoid potential 
problem
as you said.

Thank you.


      reply	other threads:[~2021-03-16  2:16 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 13:33 [PATCH v7] i2c: virtio: add a virtio i2c frontend driver Jie Deng
2021-03-12  5:53 ` Jie Deng
2021-03-12  6:10 ` Viresh Kumar
2021-03-12  7:51   ` Jie Deng
2021-03-12  8:11     ` Viresh Kumar
2021-03-12  8:37       ` Jie Deng
2021-03-16  7:39       ` Viresh Kumar
2021-03-12  8:58 ` Arnd Bergmann
2021-03-15  1:14   ` Jie Deng
2021-03-15  3:13     ` Jason Wang
2021-03-15  5:52       ` Jie Deng
2021-03-15  7:52         ` Arnd Bergmann
2021-03-16  2:15           ` Jie Deng [this message]

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