[U-Boot] gpio: Question about gpio_set_value() implementation in spear_gpio.c

[Stefan Roese <sr@denx.de>]

On 19.06.2013 16:01, Axel Lin wrote:
>>> -     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
>>> +     if (value)
>>> +             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
>>> +     else
>>> +             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
>>
>>
>> You might want to use clrbits_le32() and setbits_le32() here, no?
>>
> 
> Honestly, I ask this because I cannot find the detail datasheet for the gpio
> control of this device. ( Just found the code looks strange).
> 
> Usually we can use clrbits_le32() and setbits_le32() helpers to set/clear
> register bits. But if the only meaningful bit is "1 << gpio", simply use
> "write 1 << gpio" and "write 0" saves a register read operation.
> 
> So maybe Stefan  or someone from ST can provide the information about gpio
> control on this hardware.

I honestly have no idea how I tested this GPIO driver. That was too long
ago. And I don't have the time to dig out the hardware to do some
re-testing. But the code definitely looks wrong, so thanks for catching
this. Let's wait what the ST engineers have to comment here.

Thanks,
Stefan