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Message-id: <51ADEEF6.1030200@samsung.com>
Date: Tue, 04 Jun 2013 15:43:18 +0200
From: Sylwester Nawrocki <s.nawrocki@samsung.com>
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To: Kishon Vijay Abraham I <kishon@ti.com>
Cc: grant.likely@linaro.org, tony@atomide.com, balbi@ti.com, arnd@arndb.de,
        swarren@nvidia.com, linux-kernel@vger.kernel.org,
        linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-usb@vger.kernel.org, rob.herring@calxeda.com, rob@landley.net,
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        benoit.cousson@linaro.org, mchehab@redhat.com,
        akpm@linux-foundation.org, cesarb@cesarb.net, davem@davemloft.net,
        rnayak@ti.com, shawn.guo@linaro.org, santosh.shilimkar@ti.com,
        devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
        nsekhar@ti.com
Subject: Re: [PATCH v6 1/9] drivers: phy: add generic PHY framework
References: <1367229812-30574-1-git-send-email-kishon@ti.com>
 <1367229812-30574-2-git-send-email-kishon@ti.com>
 <51ADBF9B.5060403@samsung.com> <51ADDCD9.8080400@ti.com>
In-reply-to: <51ADDCD9.8080400@ti.com>
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Hi,

On 06/04/2013 02:26 PM, Kishon Vijay Abraham I wrote:
>>> +static inline int phy_init(struct phy *phy)
>>> +{
>>> +	pm_runtime_get_sync(&phy->dev);
>>
>> Hmm, no need to check return value here ? Also it looks a bit unexpected to
> 
> I purposely dint check the return values in order to support platforms 
> that don?t enable pm_runtime.

Then I guess this should be called conditionally and any errors returned
if runtime PM is enabled ? Not sure if pm_runtime_enabled() would be
helpful such situation.

>> possibly have runtime_resume callback of a PHY device called before ops->init()
>> call ? It seems a bit unclear what the purpose of init() callback is.
> 
> Not really. Anything that is used to initialize the PHY (internal 
> configuration) can go in phy_init. Usually in runtime_resume callback, 
> optional functional clocks are enabled and also in some cases context 
> restore is done. So it really makes sense to enable clocks/module 
> (pm_runtime_get_sync) before doing a PHY configuration (phy_init).

OK, that makes sense. All PHY device resources must be prepared anyway
before a PHY object is registered with the PHY core.

>>> +	if (phy->ops->init)
>>> +		return phy->ops->init(phy);
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static inline int phy_exit(struct phy *phy)
>>> +{
>>> +	int ret = -EINVAL;
>>> +
>>> +	if (phy->ops->exit)
>>> +		ret = phy->ops->exit(phy);
>>> +
>>> +	pm_runtime_put_sync(&phy->dev);
>>> +
>>> +	return ret;
>>> +}
>>
>> Do phy_init/phy_exit need to be mandatory ? What if there is really
> 
> No. phy_init/phy_exit is not mandatory at all.
>> nothing to do in those callbacks ? Perhaps -ENOIOCTLCMD should be
>> returned if a callback is not implemented, so PHY users can recognize
>> such situation and proceed ?
> 
> So currently these APIs return -EINVAL if these callbacks are not 
> populated which is good enough IMHO.

But -EINVAL could be well returned from the callback function. Perhaps
ENOTSUPP could be used instead ?


Thanks,
Sylwester
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