From: Javier Martinez Canillas <javierm@redhat.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org,
open list <linux-kernel@vger.kernel.org>,
linux-renesas-soc@vger.kernel.org,
Lee Jones <lee.jones@linaro.org>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH RFC] modpost: Support I2C Aliases from OF tables
Date: Tue, 6 Aug 2019 00:25:34 +0200 [thread overview]
Message-ID: <f4a78e93-6aaa-bc72-cf94-06fc2574451c@redhat.com> (raw)
In-Reply-To: <20190731194419.GB4084@kunai>
Hello Wolfram,
On 7/31/19 9:44 PM, Wolfram Sang wrote:
> Hi Javier,
>
> thank you for providing the extra information.
>
> (And Kieran, thanks for the patch!)
>
>> The other option is to remove i2c_of_match_device() and don't make OF match
>> to fallback to i2c_of_match_device_sysfs(). This is what happens in the ACPI
>> case, since i2c_device_match() just calls acpi_driver_match_device() directly
>> and doesn't have a wrapper function that fallbacks to sysfs matching.
>>
>> In this case an I2C device ID table would be required if the devices have to
>> be instantiated through sysfs. That way the I2C table would be used both for
>> auto-loading and also to match the device when it doesn't have an of_node.
>
> That would probably mean that only a minority of drivers will not add an I2C
> device ID table because it is easy to add an you get the sysfs feature?
>
I believe so yes.
> Then we are back again with the situation that most drivers will have
> multiple tables. With the minor change that the I2C device id table is
> not required anymore by the core, but it will be just very useful to
> have? Or?
>
Yes, it won't be needed anymore if you are only instantiating all your devices
from your firmware interface (e.g: OF, ACPI).
>> If the former is the correct way to solve this then the patch looks good to me.
>>
>> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
>
> For this actual patch from Kieran, I'd like to hear an opinion from the
> people maintaining modpost. The aproach looks okay to me, yet I can't
> tell how "easy" we are with adding new types like 'i2c_of'.
>
As Masahiro-san mentioned, this approach will still require to add a new macro
MODULE_DEVICE_TABLE(i2c_of, bar_of_match) so the OF device table is used twice.
One to expose the "of:N*T*Cfoo,bar" and another one to expose it as "i2c:bar".
I expect that many developers would miss adding this macro for new drivers that
are DT-only and so sysfs instantiation would not work there. So whatever is the
approach taken we should clearly document all this so drivers authors are aware.
> Thanks everyone,
>
> Wolfram
>
Best regards,
--
Javier Martinez Canillas
Software Engineer - Desktop Hardware Enablement
Red Hat
next prev parent reply other threads:[~2019-08-05 22:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-10 19:39 [PATCH RFC] modpost: Support I2C Aliases from OF tables Kieran Bingham
2019-07-22 13:03 ` Javier Martinez Canillas
2019-07-31 19:44 ` Wolfram Sang
2019-08-01 2:17 ` Masahiro Yamada
2019-08-05 22:48 ` Javier Martinez Canillas
2019-08-06 7:30 ` Geert Uytterhoeven
2019-08-06 17:39 ` Javier Martinez Canillas
2019-08-05 22:25 ` Javier Martinez Canillas [this message]
2019-08-06 7:22 ` Geert Uytterhoeven
2019-08-06 17:12 ` Javier Martinez Canillas
2019-08-08 13:12 ` Enrico Weigelt, metux IT consult
2019-08-08 13:24 ` Andy Shevchenko
2019-08-08 14:00 ` Enrico Weigelt, metux IT consult
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