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 _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek
next prev parent reply index 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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