linux-kernel - Re: Fwd: [PATCH 1/3] i2c: Add Device Tree support to the Nomadik I2C driver

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Message-ID: <4FDB3F6C.9000509@linaro.org>
Date:	Fri, 15 Jun 2012 14:58:04 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Srinidhi Kasagar <srinidhi.kasagar@...ricsson.com>
CC:	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: Re: Fwd: [PATCH 1/3] i2c: Add Device Tree support to the Nomadik
 I2C driver

On 15/06/12 14:37, Srinidhi Kasagar wrote:
> On Fri, Jun 15, 2012 at 15:18:58 +0200, Lee Jones wrote:
>> On 15/06/12 14:05, Srinidhi Kasagar wrote:
>>> On Fri, Jun 15, 2012 at 14:45:11 +0200, Lee Jones wrote:
>>>> On 15/06/12 12:50, Srinidhi Kasagar wrote:
>>>>> [...]
>>>>>>
>>>>>>
>>>>>> From: Lee Jones<lee.jones@...aro.org>
>>>>>> Date: Tue, 17 Apr 2012 16:04:13 +0100
>>>>>> Subject: [PATCH 1/1] i2c: Add Device Tree support to the Nomadik I2C driver
>>>>>>
>>>>>> Here we apply the bindings required for successful Device Tree
>>>>>> probing of the i2c-nomadik driver. We also apply a fall-back
>>>>>> configuration in case either one is not provided, or a required
>>>>>> element is missing from the one supplied.
>>>>>>
>>>>>> Cc: linux-i2c@...r.kernel.org
>>>>>> Signed-off-by: Lee Jones<lee.jones@...aro.org>
>>>>>> ---
>>>>>>     drivers/i2c/busses/i2c-nomadik.c |   82 +++++++++++++++++++++++++++++++++++++-
>>>>>>     1 file changed, 80 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
>>>>>> index a92440d..58e8114 100644
>>>>>> --- a/drivers/i2c/busses/i2c-nomadik.c
>>>>>> +++ b/drivers/i2c/busses/i2c-nomadik.c
>>>>>> @@ -23,6 +23,7 @@
>>>>>>     #include<linux/io.h>
>>>>>>     #include<linux/regulator/consumer.h>
>>>>>>     #include<linux/pm_runtime.h>
>>>>>> +#include<linux/of.h>
>>>>>>
>>>>>>     #include<plat/i2c.h>
>>>>>>
>>>>>> @@ -899,15 +900,86 @@ static const struct i2c_algorithm nmk_i2c_algo = {
>>>>>>           .functionality  = nmk_i2c_functionality
>>>>>>     };
>>>>>>
>>>>>> +static struct nmk_i2c_controller u8500_i2c = {
>>>>>> +       /*
>>>>>> +        * Slave data setup time; 250ns, 100ns, and 10ns, which
>>>>>> +        * is 14, 6 and 2 respectively for a 48Mhz i2c clock.
>>>>>> +        */
>>>>>> +       .slsu           = 0xe,
>
> And BTW, I forgot to mention: This slsu stuff is not needed at all.
> It is required only in case of slave mode operation, which the
> driver does not support. You can perhaps consider deprecating
> this parameter from device tree list as well as from platform data.

Thanks. I will add it to my TODO list for a latter patch-set.

>>>>>> +       .tft            = 1,      /* Tx FIFO threshold */
>>>>>> +       .rft            = 8,      /* Rx FIFO threshold */
>>>>>> +       .clk_freq       = 100000, /* std. mode operation */
>>>>>> +       .timeout        = 200,    /* Slave response timeout(ms) */
>>>>>> +       .sm             = I2C_FREQ_MODE_FAST,
>>>>>
>>>>> How is this possible? you are setting clk_freq as 100kb/s and mode
>>>>> as fast mode which is supposed to be 400kb/s.
>>>>
>>>> That's not how I read it:
>>>
>>> But it is not readable. It confuses people.
>>
>> I understood it. :)
>>
>> If you think it's unclear speak to the author, Linus. He's CC'ed.
>
> It is!
>
> /srinidhi


-- 
Lee Jones
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