From: Wolfram Sang <w.sang@pengutronix.de>
To: Roland Stigge <stigge@antcom.de>
Cc: vitalywool@gmail.com, khali@linux-fr.org, ben-linux@fluff.org,
grant.likely@secretlab.ca, linux-i2c@vger.kernel.org,
linux-kernel@vger.kernel.org, kevin.wells@nxp.com,
srinivas.bakki@nxp.com, aletes.xgr@gmail.com, jonsmirl@gmail.com
Subject: Re: [PATCH RESEND 2/2] i2c: pnx: Fix read transactions of >= 2 bytes
Date: Sat, 18 Aug 2012 11:52:12 +0200 [thread overview]
Message-ID: <20120818095212.GC24812@pengutronix.de> (raw)
In-Reply-To: <1344411752-23469-2-git-send-email-stigge@antcom.de>
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On Wed, Aug 08, 2012 at 09:42:32AM +0200, Roland Stigge wrote:
> On transactions with n>=2 bytes, the controller actually wrongly clocks in n+1
> bytes. This is caused by the (wrong) assumption that RFE in the Status Register
> is 1 iff there is no byte already ordered (via a dummy TX byte). This lead to
> the implementation of synchronized byte ordering, e.g.:
>
> Dummy-TX - RX - Dummy-TX - RX - ...
>
> But since RFE actually stays high after some Dummy-TX, it rather looks like:
>
> Dummy-TX - Dummy-TX - RX - Dummy-TX - RX - (RX)
>
> The last RX byte is clocked in by the bus controller, but ignored by the kernel
> when filling the userspace buffer.
>
> This patch fixes the issue by asking for RX via Dummy-TX asynchronously.
> Introducing a separate counter for TX bytes.
>
> Signed-off-by: Roland Stigge <stigge@antcom.de>
>
> ---
> Applies to v3.6-rc1
>
> This patch for i2c-pnx affects PNX4008 and LPC32xx (and LPC31xx, not yet in
> mainline). Can you please test?
>
> Thanks in advance!
I assume you checked this on LPC32xx? I'll wait a bit more but tend to
take the patch anyhow, even if there is no explicit ACK from PNX.
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next prev parent reply other threads:[~2012-08-18 9:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-08 7:42 [PATCH RESEND 1/2] i2c: pnx: Fix bit definitions Roland Stigge
2012-08-08 7:42 ` [PATCH RESEND 2/2] i2c: pnx: Fix read transactions of >= 2 bytes Roland Stigge
2012-08-18 9:52 ` Wolfram Sang [this message]
2012-08-19 8:45 ` Roland Stigge
2012-08-18 9:51 ` [PATCH RESEND 1/2] i2c: pnx: Fix bit definitions Wolfram Sang
2012-08-19 8:47 ` Roland Stigge
2012-08-20 16:26 ` Kevin Wells
2012-08-20 16:47 ` Roland Stigge
2012-08-20 19:49 ` Arnd Bergmann
2012-08-20 17:55 ` Wolfram Sang
2012-08-20 20:47 ` Roland Stigge
2012-09-03 20:16 ` Roland Stigge
2012-09-04 9:20 ` Wolfram Sang
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