linux-spi.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Ray Jui <rjui@broadcom.com>
To: Mark Brown <broonie@kernel.org>, Grant Likely <grant.likely@linaro.org>
Cc: <linux-spi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	JD Zheng <jdzheng@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>
Subject: Re: [PATCH] spi: pl022: Fix broken spidev when DMA is enabled
Date: Wed, 8 Oct 2014 09:14:35 -0700	[thread overview]
Message-ID: <543562EB.8060300@broadcom.com> (raw)
In-Reply-To: <20141008112143.GT4609@sirena.org.uk>



On 10/8/2014 4:21 AM, Mark Brown wrote:
> On Tue, Oct 07, 2014 at 09:38:47PM -0700, Ray Jui wrote:
>
>> The PL022 SPI driver maps the DMA RX buffer before the DMA TX buffer. In
>> most cases, the sequence of the mapping does not matter. But in cases
>> where TX and RX happen to use the same buffer, e.g., spidev, it causes
>> the cached TX data not written to memory, because the same memory has
>> been marked invalid when dma_map_sg on the RX buffer is called
>
> This seems like it is a bug in spidev, using the same buffer simultaneously
> for both directions isn't something I'd think would be expected to work
> reliably unless it was explicitly mapped as bidirectional.
>
Hi Mark,

Thanks for the reply. It looks like you are also the maintainer of 
spidev. In this case, could you please help to confirm that you expect 
spidev to use separate buffers for TX and RX? If so, I can go ahead and 
make the change in spidev.

+ Grant

Thanks,

Ray

  reply	other threads:[~2014-10-08 16:14 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Ray Jui <rjui@broadcom.com>
2014-10-09 18:19 ` [PATCH] spi: spidev: Use separate TX and RX bounce buffers Ray Jui
     [not found]   ` <1412878765-29088-1-git-send-email-rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2014-10-13 11:07     ` Mark Brown
     [not found]       ` <20141013110726.GT27755-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2014-10-14  3:05         ` Ray Jui
     [not found] ` <Ray Jui <rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2014-10-08  4:38   ` [PATCH] spi: pl022: Fix broken spidev when DMA is enabled Ray Jui
     [not found]     ` <1412743127-4523-1-git-send-email-rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2014-10-08 11:21       ` Mark Brown
2014-10-08 16:14         ` Ray Jui [this message]
     [not found]           ` <543562EB.8060300-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2014-10-08 18:21             ` Mark Brown
     [not found]               ` <20141008182123.GH4609-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2014-10-08 18:31                 ` Ray Jui
2014-10-09 13:59                 ` Geert Uytterhoeven
2014-10-09 18:44   ` [PATCH] spi: pl022: Fix incorrect dma_unmap_sg Ray Jui
     [not found]     ` <1412880294-9860-1-git-send-email-rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2014-10-13 11:08       ` Mark Brown
     [not found]         ` <20141013110851.GU27755-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2014-10-14  3:05           ` Ray Jui

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=543562EB.8060300@broadcom.com \
    --to=rjui@broadcom.com \
    --cc=broonie@kernel.org \
    --cc=grant.likely@linaro.org \
    --cc=jdzheng@broadcom.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-spi@vger.kernel.org \
    --cc=sbranden@broadcom.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).