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Subject: Re: [greybus-dev] [PATCH] staging: greybus: Use gpio_is_valid()
To:     Alex Elder <elder@linaro.org>, hvaibhav.linux@gmail.com,
        johan@kernel.org, elder@kernel.org, gregkh@linuxfoundation.org
References: <785eda4d65f396b353393e9538eba21095ce876e.1524825902.git.arvind.yadav.cs@gmail.com>
 <7ebee672-6413-6f1d-fe57-2e278c90cf9e@linaro.org>
Cc:     devel@driverdev.osuosl.org, greybus-dev@lists.linaro.org,
        linux-kernel@vger.kernel.org
From:   Arvind Yadav <arvind.yadav.cs@gmail.com>
Message-ID: <3910023d-143e-7618-1fd4-f3bdffbfb3ec@gmail.com>
Date:   Fri, 27 Apr 2018 18:20:37 +0530
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On Friday 27 April 2018 05:47 PM, Alex Elder wrote:
> On 04/27/2018 05:52 AM, Arvind Yadav wrote:
>> Replace the manual validity checks for the GPIO with the
>> gpio_is_valid().
> I haven't looked through the code paths very closely, but I
> think that get_named_gpio() might return -EPROBE_DEFER, which
> would be something we want to pass to the caller.
Yes of_get_name_gpio() can return other error value apart from
-EPROBE_DEFER.
> So rather than returning -ENODEV and hiding the reason the
> call to of_get_named_gpio() failed, you should continue
> returning the errno it supplies (if not a valid gpio number).
>
> 					-Alex
I have return -ENODEV because invalid gpio pin can be positive.
static inline bool gpio_is_valid(int number)
{
     return number >= 0 && number < ARCH_NR_GPIOS;
}
Here if number > ARCH_NR_GPIOS then it's invalid but return value
will be positive.

We can return like this
     " return (gpio > 0) ? -ENODEV: gpio;"

But not sure this is worth to handle this.

~arvind
>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
>> ---
>>   drivers/staging/greybus/arche-platform.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
>> index 83254a7..fc6bf60 100644
>> --- a/drivers/staging/greybus/arche-platform.c
>> +++ b/drivers/staging/greybus/arche-platform.c
>> @@ -448,9 +448,9 @@ static int arche_platform_probe(struct platform_device *pdev)
>>   	arche_pdata->svc_reset_gpio = of_get_named_gpio(np,
>>   							"svc,reset-gpio",
>>   							0);
>> -	if (arche_pdata->svc_reset_gpio < 0) {
>> +	if (!gpio_is_valid(arche_pdata->svc_reset_gpio)) {
>>   		dev_err(dev, "failed to get reset-gpio\n");
>> -		return arche_pdata->svc_reset_gpio;
>> +		return -ENODEV;
>>   	}
>>   	ret = devm_gpio_request(dev, arche_pdata->svc_reset_gpio, "svc-reset");
>>   	if (ret) {
>> @@ -468,9 +468,9 @@ static int arche_platform_probe(struct platform_device *pdev)
>>   	arche_pdata->svc_sysboot_gpio = of_get_named_gpio(np,
>>   							  "svc,sysboot-gpio",
>>   							  0);
>> -	if (arche_pdata->svc_sysboot_gpio < 0) {
>> +	if (!gpio_is_valid(arche_pdata->svc_sysboot_gpio)) {
>>   		dev_err(dev, "failed to get sysboot gpio\n");
>> -		return arche_pdata->svc_sysboot_gpio;
>> +		return -ENODEV;
>>   	}
>>   	ret = devm_gpio_request(dev, arche_pdata->svc_sysboot_gpio, "sysboot0");
>>   	if (ret) {
>> @@ -487,9 +487,9 @@ static int arche_platform_probe(struct platform_device *pdev)
>>   	arche_pdata->svc_refclk_req = of_get_named_gpio(np,
>>   							"svc,refclk-req-gpio",
>>   							0);
>> -	if (arche_pdata->svc_refclk_req < 0) {
>> +	if (!gpio_is_valid(arche_pdata->svc_refclk_req)) {
>>   		dev_err(dev, "failed to get svc clock-req gpio\n");
>> -		return arche_pdata->svc_refclk_req;
>> +		return -ENODEV;
>>   	}
>>   	ret = devm_gpio_request(dev, arche_pdata->svc_refclk_req,
>>   				"svc-clk-req");
>>