linux-kernel - Re: [PATCH RFC] gpiolib: ensure that fwnode is properly set

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Message-ID: <1cad3684-cc4a-9c45-c52c-95ffc2cdb680@quicinc.com>
Date:   Tue, 15 Nov 2022 13:48:33 +0530
From:   Shazad Hussain <quic_shazhuss@...cinc.com>
To:     Robert Marko <robimarko@...il.com>,
        Brian Masney <bmasney@...hat.com>, <linus.walleij@...aro.org>,
        <brgl@...ev.pl>
CC:     <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <psodagud@...cinc.com>,
        <quic_ppareek@...cinc.com>, <ahalaney@...hat.com>,
        <echanude@...hat.com>, <nicolas.dechesne@...aro.org>
Subject: Re: [PATCH RFC] gpiolib: ensure that fwnode is properly set


On 11/15/2022 2:32 AM, Robert Marko wrote:
> 
> On 14. 11. 2022. 21:29, Brian Masney wrote:
>> Note that this is a RFC patch and not meant to be merged. I looked into
>> a problem with linux-next-20221110 on the Qualcomm SA8540P automotive
>> board (sc8280xp) where the UFS host controller would fail to probe due
>> to repeated probe deferrals when trying to get reset-gpios via
>> devm_gpiod_get_optional().
>>
>> of_get_named_gpiod_flags() returns -EPROBE_DEFER, which is caused by
>> of_gpiochip_match_node_and_xlate() returning 0 since the of_xlate 
>> function
>> pointer is not set for the qcom,sc8280xp-tlmm pinctrl driver. The
>> pinctrl driver doesn't define one, so of_gpiochip_add() should
>> automatically setup of_gpio_simple_xlate() on it's behalf. This doesn't
>> happen since the fwnode member on the struct gpiochip is set to null
>> when of_gpiochip_add() is called. Let's work around this by ensuring
>> that it's set if available.
>>
>> Note that this broke sometime within the last few weeks within
>> linux-next and I haven't bisected this. I'm posting this in the hopes
>> that someone may know offhand which patch(es) may have broken this.
> 
> Hi, the following patch should fix it for you, I have hit the same issue on
> IPQ8074.
> 
> https://patchwork.ozlabs.org/project/linux-gpio/patch/20221111113732.461881-1-thierry.reding@gmail.com/
>
This fixes the issue I was facing for sa8540p (sc8280xp). Thanks Robert.

Shazad

> Regards,
> Robert
> 
>>
>> Signed-off-by: Brian Masney <bmasney@...hat.com>
>> ---
>>   drivers/gpio/gpiolib.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> index 11fb7ec883e9..8bec66008869 100644
>> --- a/drivers/gpio/gpiolib.c
>> +++ b/drivers/gpio/gpiolib.c
>> @@ -678,7 +678,7 @@ int gpiochip_add_data_with_key(struct gpio_chip 
>> *gc, void *data,
>>        * Assign fwnode depending on the result of the previous calls,
>>        * if none of them succeed, assign it to the parent's one.
>>        */
>> -    gdev->dev.fwnode = dev_fwnode(&gdev->dev) ?: fwnode;
>> +    gc->fwnode = gdev->dev.fwnode = dev_fwnode(&gdev->dev) ?: fwnode;
>>       gdev->id = ida_alloc(&gpio_ida, GFP_KERNEL);
>>       if (gdev->id < 0) {