linux-kernel - Re: [PATCH v2] staging: greybus: Use gpio_is

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Message-ID: <2aa263ef-1bbc-69fc-c007-303e59517081@gmail.com>
Date:   Wed, 2 May 2018 15:15:05 +0530
From:   Arvind Yadav <arvind.yadav.cs@...il.com>
To:     Johan Hovold <johan@...nel.org>
Cc:     hvaibhav.linux@...il.com, elder@...nel.org,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        greybus-dev@...ts.linaro.org, devel@...verdev.osuosl.org
Subject: Re: [PATCH v2] staging: greybus: Use gpio_is_valid()



On Wednesday 02 May 2018 02:13 PM, Johan Hovold wrote:
> On Sat, Apr 28, 2018 at 10:05:39AM +0530, Arvind Yadav wrote:
>> Replace the manual validity checks for the GPIO with the
>> gpio_is_valid().
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>> chnage in v2 :
>>               Returning invalid gpio as error instead of -ENODEV.
>>
>>   drivers/staging/greybus/arche-platform.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
>> index 83254a7..c3a7da5 100644
>> --- a/drivers/staging/greybus/arche-platform.c
>> +++ b/drivers/staging/greybus/arche-platform.c
>> @@ -448,7 +448,7 @@ 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;
> I'm sorry, but I don't this change is desirable. of_get_named_gpio()
> returns a valid gpio number or a negative errno, so there's no need to
> use the legacy gpio_is_valid() helper here.
>
> If you grep for of_get_named_gpio() you'll find that some drivers indeed
> use that helper this way, but they are in a clear minority.
>
> And ultimately, we want to move to using gpio descriptors anyway.

We need to check gpio validity. If we are using of_get_named_gpio() or not.
of_get_name_gpio() will read a device node and fetch the value. But 
it'll not
check that gpio is valid or not valid.
>
>>   	}
>> @@ -468,7 +468,7 @@ 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;
>>   	}
>> @@ -487,7 +487,7 @@ 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;
>>   	}
> But if this were to be changed, you'd need to update also the fourth
> call to of_get_named_gpio() in this function.

Sorry, I missed it. Thanks for point out. I will add check for this.

~arvind
>
> Thanks,
> Johan