On 01/24/2013 09:43 AM, Joachim Eastwood wrote:

On 24 January 2013 08:58, ludovic.desroches [off-list ref] wrote:

quoted

Hi,


On 01/24/2013 08:27 AM, Wolfram Sang wrote:

quoted

On Tue, Dec 18, 2012 at 07:02:32AM +0100, Jean-Christophe PLAGNIOL-VILLARD
wrote:

quoted

On 22:42 Wed 05 Dec     , Joachim Eastwood wrote:

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Signed-off-by: Joachim Eastwood <redacted>
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Hi,

AT91RM9200 is gaining DT support now so let's add an id to the i2c
driver.

Tested on custom RM9200 board. Since the driver doesn't support pinctrl
muxing yet I had to add pinctrl hogs for the i2c pins in my dts for it
to work.

IIRC the i2c IP have quite a lots of issue on rm9200 and until sam9g45

it not recommended to use it instead use i2c-gpio

Ludovic, you know the driver best. Does it make sense to add this?

I didn't add this when I did the rework because there was no DT tree support
for RM9200. The configuration for RM9200 IP is already in the driver and
used for non DT platform so I think it makes sense to add this.

But as Jean-Christophe said, it's recommended to use the i2c-gpio driver
since we know the first versions of the IP have several issues. However if
it fits user usage, it is not forbidden to use it.

I assumed the new driver handles the HW quirks better than the old atmel-twi
driver(?). So the RM9200 i2c HW is at least usable with this driver.

No it doesn't handle HW quirks (clock stretching, stop command, etc.) 
better for old IP versions than the old atmel-twi. Since we have no 
workarounds for these quirks, it was recommended to use i2c-gpio.

I didn't encounter any problems during my short testing using a couple of
different i2c devices. As far as I can remember the old driver didn't even
handle the devices I tested with the new driver.

I also did some tests on RM9200 with basic i2c devices and everything go 
well so yes it is usable that's why I think this patch can be applied.

Regards

Ludovic