From: Wolfram Sang <wsa@the-dreams.de>
To: Eddie Huang <eddie.huang@mediatek.com>
Cc: Sascha Hauer <kernel@pengutronix.de>,
srv_heupstream@mediatek.com, Rob Herring <robh+dt@kernel.org>,
Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
Xudong Chen <xudong.chen@mediatek.com>,
Liguo Zhang <liguo.zhang@mediatek.com>,
linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org
Subject: Re: [PATCH v7 2/3] I2C: mediatek: Add driver for MediaTek I2C controller
Date: Mon, 18 May 2015 08:37:42 +0200 [thread overview]
Message-ID: <20150518063742.GA1545@katana> (raw)
In-Reply-To: <1431928701.22349.22.camel@mtksdaap41>
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> > > + rpaddr = dma_map_single(i2c->adap.dev.parent, msgs->buf,
> > > + msgs->len, DMA_FROM_DEVICE);
> >
> > I think you shouldn't use the adapter device here and later, but the dma
> > channel device.
> >
> In MTK SoC, each I2C controller has its own DMA, and this DMA can't be
> used by other hardware.
> So I tend to use DMA directly, not through DMA channel.
> Even so, "i2c->adap.dev.parent" is not suitable here. I will change to
> use i2c->dev here. (Reference i2c-at91.c).
The better reference would be i2c-sh_mobile.c, especially commit
8cfcae9f0595bf0d145a67cfaa1051804a301d7c ("i2c: sh_mobile: use proper
device for mapping DMA memory") ;) The request to use the DMA channel
device came from the DMA folks, so if there is no real reason for an
exception, please use the channel device.
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next prev parent reply other threads:[~2015-05-18 6:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-06 8:37 [PATCH v7 0/3] ARM: mediatek: Add driver for Mediatek I2C Eddie Huang
2015-05-06 8:37 ` [PATCH v7 1/3] dt-bindings: Add I2C bindings for mt65xx/mt81xx Eddie Huang
2015-05-12 12:37 ` wsa
2015-05-12 12:45 ` Sascha Hauer
2015-05-06 8:37 ` [PATCH v7 2/3] I2C: mediatek: Add driver for MediaTek I2C controller Eddie Huang
2015-05-12 12:58 ` wsa
2015-05-18 5:58 ` Eddie Huang
2015-05-18 6:37 ` Wolfram Sang [this message]
2015-05-18 7:42 ` Eddie Huang
2015-05-18 9:05 ` Wolfram Sang
2015-05-06 8:37 ` [PATCH v7 3/3] I2C: mediatek: Add driver for MediaTek MT8173 " Eddie Huang
2015-05-12 13:00 ` wsa
2015-05-07 7:39 ` [PATCH v7 0/3] ARM: mediatek: Add driver for Mediatek I2C Lee Jones
2015-05-07 7:54 ` Eddie Huang
2015-05-07 8:27 ` Lee Jones
2015-05-12 12:45 ` Sascha Hauer
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