From: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Ray Jui <rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
JD Zheng <jdzheng-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>,
Scott Branden <sbranden-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
Subject: Re: [PATCH] spi: pl022: Fix broken spidev when DMA is enabled
Date: Wed, 8 Oct 2014 12:21:43 +0100 [thread overview]
Message-ID: <20141008112143.GT4609@sirena.org.uk> (raw)
In-Reply-To: <1412743127-4523-1-git-send-email-rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
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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.
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next prev parent reply other threads:[~2014-10-08 11:21 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 [this message]
2014-10-08 16:14 ` Ray Jui
[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
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