[lkml]   [2020]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2] mtd: mtk-quadspi: add support for DMA reading

On Mon, Feb 10, 2020 at 4:31 PM Yingjoe Chen <> 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.

Chuanhong Guo

 \ /
  Last update: 2020-02-11 07:57    [W:0.117 / U:30.928 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site