linux-kernel - Re: [PATCH v3 2/3] i2c: designware: detect when dynamic tar update is possible

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Message-ID: <c58ce503-580b-34b7-3489-7b8829f88dca@linux.intel.com>
Date:	Wed, 17 Aug 2016 11:05:34 +0300
From:	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:	"De Marchi, Lucas" <lucas.demarchi@...el.com>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Cc:	"mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"christian.ruppert@...tech.com" <christian.ruppert@...tech.com>,
	"Souza, Jose" <jose.souza@...el.com>
Subject: Re: [PATCH v3 2/3] i2c: designware: detect when dynamic tar update is
 possible

On 08/16/2016 05:07 PM, De Marchi, Lucas wrote:
> On Tue, 2016-08-16 at 17:00 +0300, Jarkko Nikula wrote:
>>> +	 */
>>> +	reg = dw_readl(dev, DW_IC_CON);
>>> +	dw_writel(dev, reg ^ DW_IC_CON_10BITADDR_MASTER,
>>> DW_IC_CON);
>>> +
>>> +	if ((dw_readl(dev, DW_IC_CON) &
>>> DW_IC_CON_10BITADDR_MASTER) ==
>>> +	    (reg & DW_IC_CON_10BITADDR_MASTER)) {
>>> +		dev->dynamic_tar_update_enabled = true;
>>> +		dev_dbg(dev->dev, "Dynamic TAR update enabled");
>>> +	}
>>
>> Is this possible to move to i2c_dw_probe()? I guess the enabled
>> status
>> doesn't change runtime?
>
> It was actually useful at this place during development of this patch
> because we could check any unexpected change in behavior when resuming.
> We did catch a bug because of this and fixed.
> I'm not sure if now it makes more sense to move to probe method. I'd
> leave it where it is, but I'm open to move it there.
>
Can you do a quick re-test that case to see does it change runtime? If 
it does then this needs a comment why there is need to do this check 
each time when HW is reinitialized. Otherwise there is chance someone 
may move this code to probe time in the future.

-- 
Jarkko