On Thu, Sep 15, 2011 at 3:39 AM, Marek Vasut <marek.va...@gmail.com> wrote:
> On Friday, July 29, 2011 08:55:14 AM Jason Hui wrote:
>> Hi, Marek,
>>
>> On Thu, Jul 14, 2011 at 5:58 AM, Marek Vasut <marek.va...@gmail.com> wrote:
>> > Rewrite the mxc_i2c driver.
>> > * This version is much closer to Linux implementation.
>> > * Fixes IPG_PERCLK being incorrectly used as clock source
>> > * Fixes behaviour of the driver on iMX51
>> > * Clean up coding style a bit ;-)
>>
>> why you change i2c clock from IPG_PERCLK to IPG_CLK?
>>
>> [...]
>
> Ok, I investigated a bit deeper and I suspect the clock.c is the culprit.
>
> Apparently, the PERCLK doesn't run at the frequency the clock.c reports it
> runs
> on. Therefore, the i2c miscalculates the divider etc -- falling crap model
> (waterfall model).
But apparently, the i2c function clock should be IPG_PERCLK not IPG
clock. And Linux also fix it already.
commit 9d73242458d9a2fe26e2e240488063d414eacb1c
Author: Lothar Waßmann <l...@karo-electronics.de>
Date: Mon Jul 4 15:52:17 2011 +0200
mach-mx5: fix the I2C clock parents
The clock from which the I2C timing is derived is the ipg_perclk
not ipg_clk.
I2C bus frequency was lower by a factor of ~8 due to the clock divider
calculation being based on 66.5MHz IPG clock while the bus actually
uses 8MHz ipg_perclk.
Kernel version: 3.0.0-rc2 branch 'imx-for-next' of
git://git.pengutronix.de/git/imx/linux-2.6
Signed-off-by: Lothar Waßmann <l...@karo-electronics.de>
Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
>
> Anyway, Jason, can you look into that clock problem? I think there are more
> than
> just perclk miscalculated.
OK, I will check that part.
Jason
>
> Cheers
>
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