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From: Chuanhong Guo <gch981213@gmail.com>
To: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <tudor.ambarus@microchip.com>,
	Richard Weinberger <richard@nod.at>,
	open list <linux-kernel@vger.kernel.org>,
	linux-mediatek@lists.infradead.org,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	linux-mtd@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] mtd: mtk-quadspi: add support for DMA reading
Date: Tue, 11 Feb 2020 14:55:17 +0800
Message-ID: <CAJsYDVLzwWfT24NGDJMJShwoG0Qrq06mLqamHbH0xedmMLdrAQ@mail.gmail.com> (raw)
In-Reply-To: <1581323455.2213.6.camel@mtksdaap41>

Hi!

On Mon, Feb 10, 2020 at 4:31 PM Yingjoe Chen <yingjoe.chen@mediatek.com> wrote:
> > DMA busy checking is implemented with readl_poll_timeout because
> > I don't have access to IRQ-related docs. The speed increment comes
> > from those saved cmd+addr+dummy clocks.
>
> Hi Chuanhong,
>
> Thanks for your patch, I'm checking with Guochun to see if we could
> release IRQ related information to you.

Thanks for the info.
I'd like to keep using polling mode in this patch for easier reviewing.
It's already a pretty lengthy patch now. I may implement IRQ support
in future patches.

>
> > This controller requires that DMA source/destination address and
> > reading length should be 16-byte aligned. We use a bounce buffer if
> > one of them is not aligned, read more than what we need, and copy
> > data from corresponding buffer offset.
>
> I've checked with our HW guys. The limitation is on DRAM only.
> So for read we should check buffer and length to make sure it is
> aligned, but don't need to check from.

My previous test on mt7629 shows that from address also needs to
be aligned. e.g. If I perform a DMA read from 0x2 I actually got data
starting from 0x0 instead.

Regards,
Chuanhong Guo

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Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-08  8:40 Chuanhong Guo
2020-02-10  8:30 ` Yingjoe Chen
2020-02-11  6:55   ` Chuanhong Guo [this message]
2020-02-15  7:06 ` Chuanhong Guo

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