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From: Mark Brown <broonie@kernel.org>
To: Andy Gross <agross@codeaurora.org>
Cc: "Ivan T. Ivanov" <iivanov@mm-sol.com>,
	Bjorn Andersson <bjorn.andersson@sonymobile.com>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] spi: qup: Fix incorrect block transfers
Date: Wed, 24 Sep 2014 09:30:35 +0100	[thread overview]
Message-ID: <20140924083035.GY4015@sirena.org.uk> (raw)
In-Reply-To: <20140923192613.GA5975@qualcomm.com>

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On Tue, Sep 23, 2014 at 02:26:13PM -0500, Andy Gross wrote:
> On Tue, Sep 23, 2014 at 12:24:27PM +0300, Ivan T. Ivanov wrote:
> > On Sun, 2014-09-21 at 23:27 -0500, Andy Gross wrote:

> > > This patch fixes a number of errors with the QUP block transfer mode.  Errors
> > > manifested themselves as input underruns, output overruns, and timed out
> > > transactions.

> > At what speeds are you seeing those errors?

> We've tried 25MHz and 50MHz.  Both fail in the same way.  Keep in mind this is
> definitely a timing / race issue and it probably also dependent on the latency
> of the attached device.  I cannot reproduce this at all on my IPQ8064 based
> board, but others can.

With SPI everything is entirely clocked from the master - the attached
device can't cause any of those issues unless there's an electrical
problem that *really* upsets the master.

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      reply	other threads:[~2014-09-24  8:30 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-22  4:27 [PATCH] spi: qup: Fix incorrect block transfers Andy Gross
2014-09-23  9:24 ` Ivan T. Ivanov
2014-09-23 19:26   ` Andy Gross
2014-09-24  8:30     ` Mark Brown [this message]

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