[U-Boot] [PATCH V2] arm: omap: i2c: don't zero cnt in i2c_write

[Lokesh Vutla]

Hi Lubomir,
On Monday 02 December 2013 09:17 PM, Lubomir Popov wrote:
> Hi Nikita,
> 
> On 28/11/13 18:04, Nikita Kiryanov wrote:
>> Writing zero into I2Ci.I2C_CNT register causes random I2C failures in OMAP3
>> based devices. This seems to be related to the following advisory which
>> apears in multiple erratas for OMAP3 SoCs (OMAP35xx, DM37xx), as well as
>> OMAP4430 TRM:
>>
>> Advisory:
>> I2C Module Does Not Allow 0-Byte Data Requests
>> Details:
>> When configured as the master, the I2C module does not allow 0-byte data
>> transfers. Note: Programming I2Ci.I2C_CNT[15:0]: DCOUNT = 0 will cause
>> undefined behavior.
>> Workaround(s):
>> No workaround. Do not use 0-byte data requests.
>>
>> The writes in question are unnecessary from a functional point of view.
>> Most of them are done after I/O has finished, and the only one that preceds
>> I/O (in i2c_probe()) is also unnecessary because a stop bit is sent before
>> actual data transmission takes place.
>>
>> Therefore, remove all writes that zero the cnt register.
>>
>> Cc: Heiko Schocher <hs at denx.de>
>> Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
>> Cc: Tom Rini <trini at ti.com>
>> Cc: Lubomir Popov <lpopov at mm-sol.com>
>> Cc: Enric Balletbo Serra <eballetbo at gmail.com>
>> Signed-off-by: Nikita Kiryanov <nikita at compulab.co.il>
>> ---
>> Changes in V2:   
>>     Removed all instances of writew(0, &i2c_base->cnt) instead of just the
>>     one in i2c_write (following a test of V1 by Thomas Petazzoni).
>>
>>
> Tested-by: Lubomir Popov <lpopov at mm-sol.com>
> 
> In addition to the OMAP5430/32 tests performed last week, tested today
> on OMAP4 (4430/60/70) and on AM3359. Thus tests have covered OMAP4/5-
> compatible I2C IPs with revnb_lo=[0x000a to 0x000c] (revnb_hi is 0x5040
> for all those IPs).
May I know on top of which tree,tag you are trying this patch ?
I tried OMAP4 on top of v2014.01-rc1, but I am not able to boot. I applied this patch and still
not able to boot. There is a mail thread going on, on this topic.
So I just wanted to know that I am not missing very obvious. 

Thanks and regards,
Lokesh
>