Messages in this thread |  | | Subject | Re: [greybus-dev] [PATCH] staging: greybus: Use gpio_is_valid() | From | arvindY <> | Date | Sat, 28 Apr 2018 10:00:15 +0530 |
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On Friday 27 April 2018 06:32 PM, Alex Elder wrote: > On 04/27/2018 07:50 AM, Arvind Yadav wrote: >> >> 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. > Your reasoning is good. However in all three of these cases, > the GPIO number you're checking is the value returned from > of_get_named_gpio(). The return value is a "GPIO number to > use with Linux generic GPIO API, or one of the errno value." > > So unless the API of of_get_named_gpio() changes, you can be > sure that if the value returned is invalid, it is a negative > errno. (And if the API did change, the person making that > change would be responsible for fixing all callers to ensure > the change didn't break them.) > > This distinction may be why the code you're changing was only > testing for negative, rather than using gpio_is_valid() (you'll > see it's used elsewhere in the Greybus code--even in the same > source files.) > > Anyway, changing the code to use gpio_is_valid() is fine. But > you should avoid obscuring the reason for the error that the > return value from of_get_named_gpio() provides. > > -Alex
Yes, It'll be fine to return a invalid gpio as error instead of -ENODEV. I will send an updated patch.
~arvind > >> 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"); >>>>
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