From mboxrd@z Thu Jan  1 00:00:00 1970
From: LW@KARO-electronics.de (=?utf-8?Q?Lothar_Wa=C3=9Fmann?=)
Date: Fri, 9 Sep 2011 13:10:59 +0200
Subject: [PATCH REPOST 2/2] i2c-imx: add device tree probe support
In-Reply-To: <20110909110433.GH31581@S2100-06.ap.freescale.net>
References: <1315465775-31335-1-git-send-email-shawn.guo@linaro.org>
	<1315465775-31335-3-git-send-email-shawn.guo@linaro.org>
	<4E69A0AE.1060004@gmail.com>
	<20110909071845.GI28816@pengutronix.de>
	<20110909110433.GH31581@S2100-06.ap.freescale.net>
Message-ID: <20073.62531.113012.793381@ipc1.ka-ro>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

Shawn Guo writes:
> On Fri, Sep 09, 2011 at 09:18:45AM +0200, Uwe Kleine-K?nig wrote:
> > Hello Rob,
> > 
> > On Fri, Sep 09, 2011 at 12:14:22AM -0500, Rob Herring wrote:
> > > > +i2c at 83fc4000 { /* I2C2 on i.MX51 */
> > > > +	compatible = "fsl,imx51-i2c", "fsl,imx1-i2c";
> > > > +	reg = <0x83fc4000 0x4000>;
> > > > +	interrupts = <63>;
> > > > +};
> > > > +
> > > > +i2c at 70038000 { /* HS-I2C on i.MX51 */
> > > 
> > > The mainline driver doesn't support the HS-I2C block does it?
> > > 
> > > The high speed and "old" i2c blocks on MX51 are basically different
> > > blocks, so the compatible property should be different.
> > I stumbled about that recently, too and found in
> > arch/arm/plat-mxc/devices/platform-imx-i2c.c that the third device
> > description for imx51 is a normal "imx-i2c" one using
> > MX51_HSI2C_DMA_BASE_ADDR. So I concluded it's different but compatible.
> > 
> > board-mx51_babbage.c uses imx51_add_hsi2c but doesn't add a bus
> > description. So It might not attract attention if the driver doesn't
> > match the device.
> > 
> Aha, I was confused by the platform codes.  Will drop HSI2C.
> 
According to the i.MX51 Ref. Manual it's so buggy that it should not even
be used:
|Chapter 39
|High Speed Inter IC (HS-I2C)
|39.1 Introduction
[...]
|                                   NOTE
|Due to limited functionality, Freescale does not recommend users
|incorporate the HS-I2C module in future designs. For details on the
|limitations, refer to the MX51 IC Errata. Users should consider using the
|two standard I2C modules, which have no errata.

Fortunately there is an i2c-gpio driver that can be used on the
corresponding pins. ;-)


Lothar Wa?mann
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