linux-kernel - Re: [PATCH v5 0/4] ata: ahci_platform: Add PHY support and OMAP support

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Message-ID: <52DE6114.20601@ti.com>
Date:	Tue, 21 Jan 2014 13:59:16 +0200
From:	Roger Quadros <rogerq@...com>
To:	Hans de Goede <hdegoede@...hat.com>, <tj@...nel.org>,
	<kishon@...com>
CC:	<sergei.shtylyov@...entembedded.com>, <b.zolnierkie@...sung.com>,
	<arnd@...db.de>, <linux-ide@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v5 0/4] ata: ahci_platform: Add PHY support and OMAP support

On 01/21/2014 10:34 AM, Roger Quadros wrote:
> On 01/20/2014 06:48 PM, Hans de Goede wrote:
>> Hi,
>>
>> On 01/20/2014 03:41 PM, Roger Quadros wrote:
>>> Hi,
>>>
>>> Some platforms have a PHY hooked up to the SATA controller.
>>> The PHY needs to be initialized and powered up for SATA to work.
>>> We do that using the Generic PHY framework in PATCH 3.
>>>
>>> In order to support SATA on the OMAP platforms we need to runtime
>>> resume the device before use. PATCH 4 takes care of that.
>>
>> Thanks for keeping me in the loop on this. I'm afraid this conflicts
>> quite a bit with my recent ahci_platform.c work, not a big problem
>> really, the series can go in either way.
>>
>> Your phy support will slot nicely into the new ahci_platform_get_resources
>> and ahci_platform_enable_resources functions my refactoring introduces,
>> looking at it from this pov it might be better / easier to rebase your series
>> on top of the v4 of my series I've just send.
>>
>> Which brings me to one comment about your series why are you not doing phy_exit
>> and phy_init on suspend resp. resume ? The phy can use quite a bit of power,
>> if the phy init / exit end up in ahci_platform_enable_resources /
>> ahci_platform_disable_resources, this will happen automatically for better or
>> worse. So it would be good to test if this would work or not ...
> 
> Right. Bartlomiej had pointed this out earlier, but I just wasn't very sure about it.
> 
> Is it sufficient to just call phy_power_off() in suspend and phy_power_on() in resume?
> Or do we call phy_exit() and phy_init() respectively as well.
> 
> Kishon, any suggestions?

OK. Answering my own question.

On OMAP platform we power down the phy in phy_power_off() and idle the DPLL in phy_exit(),
so my guess is both should be called in suspend() to save the most power.

cheers,
-roger
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