linux-kernel - Re: [PATCH 0/4] Define i2c_designware in a header file

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Date: Wed, 24 Apr 2024 09:26:38 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: linux-kernel@...r.kernel.org,
 Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>,
 Jan Dabros <jsd@...ihalf.com>, Andi Shyti <andi.shyti@...nel.org>,
 Lee Jones <lee@...nel.org>, Jiawen Wu <jiawenwu@...stnetic.com>,
 Mengyuan Lou <mengyuanlou@...-swift.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
 Andrew Lunn <andrew@...n.ch>, Duanqiang Wen <duanqiangwen@...-swift.com>,
 "open list:SYNOPSYS DESIGNWARE I2C DRIVER" <linux-i2c@...r.kernel.org>,
 "open list:WANGXUN ETHERNET DRIVER" <netdev@...r.kernel.org>
Subject: Re: [PATCH 0/4] Define i2c_designware in a header file

On 4/24/24 07:26, Andy Shevchenko wrote:
> On Tue, Apr 23, 2024 at 06:21:21PM -0700, Florian Fainelli wrote:
>> On 4/23/2024 4:56 PM, Andy Shevchenko wrote:
>>> Tue, Apr 23, 2024 at 04:36:18PM -0700, Florian Fainelli kirjoitti:
>>>> This patch series depends upon the following two patches being applied:
>>>>
>>>> https://lore.kernel.org/all/20240422084109.3201-1-duanqiangwen@net-swift.com/
>>>> https://lore.kernel.org/all/20240422084109.3201-2-duanqiangwen@net-swift.com/
>>>>
>>>> There is no reason why each driver should have to repeat the
>>>> "i2c_designware" string all over the place, because when that happens we
>>>> see the reverts like the above being necessary.
>>>
>>> Isn't that a part of ABI between drivers, i.e. whenever ones want to
>>> request_module() or so they need to know what they are doing, no?
>>
>> Yes, the drivers should know, but as evidenced by the two patches above,
>> there was still room for error. If we have to abide by a certain contract,
>> which is platform_driver::driver::name, then we might as well have a header
>> defining it no?
> 
> Maybe, I simply don't like the manipulations with parts of the device instance
> names / driver IDs / driver name, which all become mixed after this series.
> 

That is fair enough, although there is definitively an expectation that 
the clock name will match the dev_name() of the i2c bus, which is why it 
changing or shortening the names as attempted by Duanqiang ended up not 
working.

This call in i2c-designware-platdrv.c is:

dev->clk = devm_clk_get_optional(&pdev->dev, NULL);

and because the name is NULL, we end-up searching for a clock named 
dev_name(), and if we have a mismatch, then we won't find it.

So the i2c_designware name is really something we must be sticking with, 
or change *globally* for a) device(s) binding to the driver and b) a 
successful clock search.
-- 
Florian

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