linux-kernel - Re: [PATCH 1/4] net: ethernet: dwmac: add Ethernet glue logic for stm32 chip

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Message-ID: <CAJgp7zxToxdKH_UU4UpF_jW2hTGvCxOPmxoDMLfphWEcKmsYHA@mail.gmail.com>
Date:	Tue, 23 Feb 2016 14:17:21 +0100
From:	Alexandre Torgue <alexandre.torgue@...il.com>
To:	Joachim Eastwood <manabian@...il.com>
Cc:	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Giuseppe Cavallaro <peppe.cavallaro@...com>,
	netdev <netdev@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] net: ethernet: dwmac: add Ethernet glue logic for
 stm32 chip

2016-02-23 12:21 GMT+01:00 Joachim  Eastwood <manabian@...il.com>:
> On 23 February 2016 at 10:59, Alexandre Torgue
> <alexandre.torgue@...il.com> wrote:
>> 2016-02-22 22:52 GMT+01:00 Joachim  Eastwood <manabian@...il.com>:
>>> On 22 February 2016 at 15:50, Alexandre Torgue
>>> <alexandre.torgue@...il.com> wrote:
>>>> 2016-02-13 14:48 GMT+01:00 Joachim  Eastwood <manabian@...il.com>:
>>>>> On 3 February 2016 at 15:54, Alexandre TORGUE
>>>>> <alexandre.torgue@...il.com> wrote:
>>>>>> +       plat_dat->bsp_priv = dwmac;
>>>>>> +       plat_dat->init = stm32_dwmac_init;
>>>>>> +       plat_dat->exit = stm32_dwmac_exit;
>>>>>
>>>>> Instead of using these callbacks could you rather implement the PM
>>>>> callbacks directly in this driver?
>>>>> I don't think it should add much code and it will make it look more
>>>>> like standard driver. This will also give you some more control and
>>>>> flexibility in your code.
>>>>
>>>> I prefer to keep the code as it is. Glue layer is directly linked to
>>>> stmmac driver and I don't want to brake the link between the glue and
>>>> the stmmac driver.
>>>
>>> What do you mean by break the link?
>>>
>>
>> I thought that you wanted to split stmmac_pltfr_supend (glue part and
>> stmamc part), but I well understood it is not the case (sorry for
>> mistake).
>>
>>> There has been numerous of patch sets to make the stmmac "glue"
>>> drivers into more standard platform drivers.
>>> http://marc.info/?l=linux-netdev&m=143159850631093&w=2
>>> http://marc.info/?l=linux-netdev&m=143708560009851&w=2
>>> http://marc.info/?l=linux-netdev&m=143812136600541&w=2
>>>
>>> Do you see any advantage by using the init and exit hooks in your
>>> driver instead of using the standard driver PM callbacks and remove
>>> function?
>>> The only "cost" I see is slightly more boilerplate code. But since you
>>> already have init/exit functions you could easily make them into PM
>>> resume/suspend so I doubt there would be much increase in code size.
>>>
>>
>> If I well understood you want to continue the stmmac glue driver
>> rework by moving stmmac_pltfr_suspend/resume/remove in each glue
>> driver (stm32, sun, sti ....).
>
> At least I want to avoid the init/exit callbacks for new drivers like
> stm32-dwmac.
>
>
>> Each glue driver will call directly stmmac_suspend/resume/remove and
>> their own init/exit function.
>> If it is what you meant, I can do it.
>
> Yes, in your stm32 driver's suspend/resume/remove functions call
> stmmac_suspend/stmmac_resume/stmmac_dvr_remove directly. Then you
> shouldn't need to use the init/exit callbacks. Just put the need code
> in the driver's suspend/resume/remove functions instead of init/exit
> functions.
>
> For example:
> static int stm32_dwmac_resume(struct device *dev)
> {
>     struct net_device *ndev = dev_get_drvdata(dev);
>     struct plat_stmmacenet_data *plat_dat = get_stmmac_plat_data(ndev)
>     struct stm32_dwmac *dwmac =plat_dat->bsp_priv;
>
>     /* enable clocks */
>     /* set phy mode */
>
>     return stmmac_resume(ndev);
> }
>
> If it makes sense to have the enable clk/phy mode stuff in it's own
> function that is fine too.

Ok. I will send v2 with this approach. After this series I could
provide a new series to change all glues with this approach ? (but I
will not able to test on each platform).

Best regards

Alexandre
>
>
>>> One other thing;
>>> Do you need to have the PHY mode setup code in the init function which
>>> is called each time on resume?
>>
>> I can't guarantee that after a suspend the sysconfig register will
>> contain same data than before suspend.
>
> I see.
>
>
> regards,
> Joachim Eastwood