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Re: [PATCH-v3 02/11] i2c: pxa: No need to set slave addr for i2c master mode reset

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  Re: [PATCH-v3 02/11] i2c: pxa: No need to set slave addr for i2c  master mode reset Wolfram Sang <wsa@the-dreams.de> - 2015-07-10 10:20 +0200
    Re: [PATCH-v3 02/11] i2c: pxa: No need to set slave addr for i2c  master mode reset Vaibhav Hiremath <vaibhav.hiremath@linaro.org> - 2015-07-13 09:20 +0200

#1181352 — Re: [PATCH-v3 02/11] i2c: pxa: No need to set slave addr for i2c master mode reset

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On Tue, Jul 07, 2015 at 12:54:46AM +0530, Vaibhav Hiremath wrote:
> Normally i2c controller works as master, so slave addr is not needed, or it
> will impact some slave device (eg. ST NFC chip) i2c accesses, because it has
> the same i2c address with controller.

Just to make sure: Does it? As I read the code, slave interrupts are
enabled later only when slave mode is selected? Is that a HW bug? And if
so, can't the code just be moved into this #ifdef block later?

> 
> Signed-off-by: Jett.Zhou <jtzhou@marvell.com>
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
> Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
> ---
>  drivers/i2c/busses/i2c-pxa.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index f4ac8c5..023e59f 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -459,7 +459,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
>  	writel(I2C_ISR_INIT, _ISR(i2c));
>  	writel(readl(_ICR(i2c)) & ~ICR_UR, _ICR(i2c));
>  
> -	if (i2c->reg_isar)
> +	if (i2c->reg_isar && IS_ENABLED(CONFIG_I2C_PXA_SLAVE))
>  		writel(i2c->slave_addr, _ISAR(i2c));
>  
>  	/* set control register values */
> -- 
> 1.9.1
> 

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#1182551

On Friday 10 July 2015 08:26 PM, Wolfram Sang wrote:
> On Fri, Jul 10, 2015 at 07:55:31PM +0530, Vaibhav Hiremath wrote:
>>
>>
>> On Friday 10 July 2015 07:44 PM, Wolfram Sang wrote:
>>> On Fri, Jul 10, 2015 at 06:08:43PM +0530, Vaibhav Hiremath wrote:
>>>>
>>>>
>>>> On Friday 10 July 2015 01:41 PM, Wolfram Sang wrote:
>>>>> On Tue, Jul 07, 2015 at 12:54:46AM +0530, Vaibhav Hiremath wrote:
>>>>>> Normally i2c controller works as master, so slave addr is not needed, or it
>>>>>> will impact some slave device (eg. ST NFC chip) i2c accesses, because it has
>>>>>> the same i2c address with controller.
>>>>>
>>>>> Just to make sure: Does it? As I read the code, slave interrupts are
>>>>> enabled later only when slave mode is selected? Is that a HW bug? And if
>>>>> so, can't the code just be moved into this #ifdef block later?
>>>>>
>>>>
>>>> Yes we could, infact I thought about it;
>>>> but I would break recommended sequence here.
>>>
>>> And did you set the "own slave address" to a value which one of your
>>> existing i2c slaves also has (without enabling slave mode)? Did it
>>> disturb communication?
>>>
>>
>> Since slave and master mode are mutual exclusive,
>> I did not try this.
>
> Ehrm, what I meant was. Did you see the issue mentioned in the above
> commit message? Can you reproduce it? You don't need to enable slave
> mode for that, no?
>

Ohh yes,

I am able to reproduce this issue.

I have pxa1928 based board, where I have only PMIC 88PM860 connected to
I2C bus, and whenever I set slave address to 0x30 (PMIC slave address)
all I2C transaction for PMIC goes for toss.


Thanks,
Vaibhav

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