Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v1 1/1] gpiolib: Read "gpio-line-names" from a firmware
 node
To:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Roman Guskov <rguskov@dh-electronics.com>
References: <20210305120240.42830-1-andriy.shevchenko@linux.intel.com>
 <CAMRc=Mfye=O4mMiK01Q6Ok+ztSfMwMcrfaZSs+LhRxi=AM+C2w@mail.gmail.com>
 <YE8z+ohM9abBs9SD@smile.fi.intel.com> <YE9YGGB+k7CsCNDI@smile.fi.intel.com>
 <CAMRc=McLsamBwe8hSob11ustk2GUzOfYh7CcqNtxsM+6vgPENw@mail.gmail.com>
 <YE9whHhaa2XavKfj@smile.fi.intel.com>
 <CAMpxmJVUVhpcNOVQCB3p8tNpac5e5c7vRQS=-avA6Cuaag9eRw@mail.gmail.com>
 <CAHp75VfsGn=dTo+f2MtssqWpuj_Sm+LHtTaM=7oW9g8riz4xTg@mail.gmail.com>
From:   Marek Vasut <marex@denx.de>
Message-ID: <5bf6771d-5783-0a40-5a72-7ddbb9c694aa@denx.de>
Date:   Sat, 10 Apr 2021 02:45:58 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.9.0
MIME-Version: 1.0
In-Reply-To: <CAHp75VfsGn=dTo+f2MtssqWpuj_Sm+LHtTaM=7oW9g8riz4xTg@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 3/15/21 6:04 PM, Andy Shevchenko wrote:
> On Mon, Mar 15, 2021 at 6:49 PM Bartosz Golaszewski
> <bgolaszewski@baylibre.com> wrote:
>>
>> On Mon, Mar 15, 2021 at 3:34 PM Andy Shevchenko
>> <andriy.shevchenko@linux.intel.com> wrote:
>>>
>>> On Mon, Mar 15, 2021 at 03:04:37PM +0100, Bartosz Golaszewski wrote:
>>>> On Mon, Mar 15, 2021 at 1:50 PM Andy Shevchenko
>>>> <andriy.shevchenko@linux.intel.com> wrote:
>>>>>
>>>>> On Mon, Mar 15, 2021 at 12:16:26PM +0200, Andy Shevchenko wrote:
>>>>>> On Mon, Mar 15, 2021 at 10:01:47AM +0100, Bartosz Golaszewski wrote:
>>>>>>> On Fri, Mar 5, 2021 at 1:03 PM Andy Shevchenko
>>>>>>> <andriy.shevchenko@linux.intel.com> wrote:
>>>>>>
>>>>>>> Unfortunately while this may fix the particular use-case on STM32, it
>>>>>>> breaks all other users as the 'gpio-line-names' property doesn't live
>>>>>>> on dev_fwnode(&gdev->dev) but on dev_fwnode(chip->parent).
>>>>>>>
>>>>>>> How about we first look for this property on the latter and only if
>>>>>>> it's not present descend down to the former fwnode?
>>>>>>
>>>>>> Oops, I have tested on x86 and it worked the same way.
>>>>>>
>>>>>> Lemme check this, but I think the issue rather in ordering when we apply fwnode
>>>>>> to the newly created device and when we actually retrieve gpio-line-names
>>>>>> property.
>>>>>
>>>>> Hmm... I can't see how it's possible can be. Can you provide a platform name
>>>>> and pointers to the DTS that has been broken by the change?
>>>>>
>>>>
>>>> I noticed it with gpio-mockup (libgpiod tests failed on v5.12-rc3) and
>>>> the WiP gpio-sim - but it's the same on most DT platforms. The node
>>>> that contains the `gpio-line-names` is the one associated with the
>>>> platform device passed to the GPIO driver. The gpiolib then creates
>>>> another struct device that becomes the child of that node but it
>>>> doesn't copy the parent's properties to it (nor should it).
>>>>
>>>> Every driver that reads device properties does it from the parent
>>>> device, not the one in gdev - whether it uses of_, fwnode_ or generic
>>>> device_ properties.
>>>
>>> What you are telling contradicts with the idea of copying parent's fwnode
>>> (or OF node) in the current code.
>>>
>>
>> Ha! While the OF node of the parent device is indeed assigned to the
>> gdev's dev, the same isn't done in the core code for fwnodes and
>> simulated chips don't have an associated OF node, so this is the
>> culprit I suppose.
> 
> Close, but not fully correct.
> First of all it depends on the OF / ACPI / platform enumeration.
> Second, we are talking about secondary fwnode in the case where it happens.
> 
> I'm in the middle of debugging this, I'll come up with something soon I believe.

Was there ever any follow up on this ?

I would like to point out that on STM32MP1 in Linux 5.10.y, the 
gpio-line-names are still broken, and a revert of "gpiolib: generalize 
devprop_gpiochip_set_names() for device properties" is still necessary.