From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-serial@vger.kernel.org
Subject: Re: [PATCH] serial: 8250_dma: sync regions for device before transfer
Date: Fri, 13 Jun 2014 16:05:04 +0300 [thread overview]
Message-ID: <20140613130504.GA1171@xps8300> (raw)
In-Reply-To: <1402588278-15109-1-git-send-email-andriy.shevchenko@linux.intel.com>
Hi Andy,
On Thu, Jun 12, 2014 at 06:51:18PM +0300, Andy Shevchenko wrote:
> The documentation says that we have to sync DMA regions after CPU access and
> before any DMA transfer is going on. The actual DMA for buffer happens when we
> call dmaengine_submit() (*). The original code syncs data after this call which
> might lead to the corrupted data in actual stream.
>
> (*) Accordingly to the Documentation/dmaengine.txt the dmaengine_submit call
> shouldn't do the transfer, but some DMA controller drivers abuse this rule.
> Thus, we would like to have this patch until all DMA controller drivers will be
> fixed. Even after that it will be harmless.
It's probable better that we directly fix the DMA engine drivers
instead of working around the issue here.
Thanks,
--
heikki
prev parent reply other threads:[~2014-06-13 13:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-12 15:51 [PATCH] serial: 8250_dma: sync regions for device before transfer Andy Shevchenko
2014-06-13 13:05 ` Heikki Krogerus [this message]
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