linux-kernel - Re: [RFC PATCH] gpio: of: fix GPIO drivers with multiple gpio

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Date:   Tue, 25 Oct 2016 10:46:08 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Sylvain Lemieux <slemieux.tyco@...il.com>
Cc:     linux-gpio@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Alexandre Courbot <gnurou@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Axel Haslam <ahaslam@...libre.com>
Subject: Re: [RFC PATCH] gpio: of: fix GPIO drivers with multiple gpio_chip
 for a single node

2016-10-25 1:58 GMT+09:00 Sylvain Lemieux <slemieux.tyco@...il.com>:
> Hi Masahiro,
>
> On Mon, 2016-10-24 at 16:43 +0900, Masahiro Yamada wrote:
>> Sylvain Lemieux reports the LPC32xx GPIO driver is broken since
>> commit 762c2e46c059 ("gpio: of: remove of_gpiochip_and_xlate() and
>> struct gg_data").  Probably, gpio-etraxfs.c and gpio-davinci.c are
>> broken as well.
>>
>> Those drivers register multiple gpio_chip that are associated to a
>> single OF node, and their own .of_xlate() checks if the passed
>> gpio_chip is valid.
>>
>> Now, the problem is of_find_gpiochip_by_node() returns the first
>> gpio_chip found to match the given node.  So, .of_xlate() fails,
>> except for the first GPIO bank.
>>
>> Reverting the commit could be a solution, but I do not want to go
>> back to the mess of struct gg_data.  Another solution here is to
>> take the match by a node pointer and the success of .of_xlate().
>> It is a bit clumsy to call .of_xlate twice; for gpio_chip matching
>> and for really getting the gpio_desc index.  Perhaps, the long-term
>> goal might be to convert drivers to single chip registration, but
>> this commit will solve the problem until then.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> Reported-by: <slemieux.tyco@...il.com>
>> ---
>>
>>  drivers/gpio/gpiolib-of.c | 14 +++++++++-----
>>  1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
>> index ecad3f0..f996596 100644
>> --- a/drivers/gpio/gpiolib-of.c
>> +++ b/drivers/gpio/gpiolib-of.c
>> @@ -26,14 +26,18 @@
>>
>>  #include "gpiolib.h"
>>
>> -static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)
>> +static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip, void *data)
>>  {
>> -     return chip->gpiodev->dev.of_node == data;
>> +     struct of_phandle_args *gpiospec = data;
>> +
>> +     return chip->gpiodev->dev.of_node == gpiospec->np &&
>> +                                     !chip->of_xlate(chip, gpiospec, NULL);
>
> for the patch to work, the second compare of the return statement
> should be updated:
>         return chip->gpiodev->dev.of_node == gpiospec->np &&
>                chip->of_xlate(chip, gpiospec, NULL) >= 0;
>
> the patch, with this return statement, is fixing the issue;
> can you submit an updated version of your patch?
>

Thanks for correction.
I've sent v2.


-- 
Best Regards
Masahiro Yamada