From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Alessandro Rubini <rubini-list@gnudd.com>
Cc: david-b@pacbell.net, linux-input@vger.kernel.org,
linux-arm-kernel@lists.arm.linux.org.uk
Subject: Re: [PATCH] ads7846: allocate separate cache lines for tx and rx data
Date: Thu, 16 Jul 2009 08:22:26 +0100 [thread overview]
Message-ID: <20090716072226.GA8113@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20090716071529.GA28840@n2100.arm.linux.org.uk>
On Thu, Jul 16, 2009 at 08:15:29AM +0100, Russell King - ARM Linux wrote:
> On Wed, Jul 15, 2009 at 09:33:26PM +0200, Alessandro Rubini wrote:
> > >> The issue was discussed with Russell King on linux-arm-kernel.
> > >
> > > Gee, but not with the author of that driver or the maintainer of
> > > the SPI framework. Who could have pointed out instantly where
> > > the true bug resides.
> >
> > So, where is it? I don't get it I'm sorry.
>
> Clearly David has no knowledge of DMA cache line handing and has not
> read the DMA API document. I really suggest that you ignore him until
> he gets a fucking clue.
... and until that happens, I suggest you remove the ADS7846 chip from
your hardware; as that DMA stuff in the driver currently stands, it
can NEVER work on ARM or any other DMA cache incoherent CPU which uses
DMA for SPI transfers.
next prev parent reply other threads:[~2009-07-16 7:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-15 9:33 [PATCH] ads7846: allocate separate cache lines for tx and rx data Alessandro Rubini
2009-07-15 18:06 ` David Brownell
2009-07-15 19:33 ` Alessandro Rubini
2009-07-16 7:15 ` Russell King - ARM Linux
2009-07-16 7:22 ` Russell King - ARM Linux [this message]
2009-07-16 7:56 ` David Brownell
2009-07-16 7:28 ` David Brownell
2009-07-16 10:00 ` Marek Vasut
2009-07-16 15:35 ` David Brownell
2009-07-16 20:06 ` Russell King - ARM Linux
2009-07-16 7:51 ` David Brownell
2009-07-16 8:15 ` Alessandro Rubini
2009-07-16 8:35 ` David Brownell
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