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SubjectRe: [PATCH] pinctrl: nsp-gpio: fix type of iterator
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+ Reddy

On 12/23/2015 2:37 AM, Andrzej Hajda wrote:
> Iterator i declared as unsigned is always non-negative so the
> loop will never end.
>
> The problem has been detected using proposed semantic patch
> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].
>
> [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576
>
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> ---
> drivers/pinctrl/bcm/pinctrl-nsp-gpio.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c
> index 34648f6..ad5b04c 100644
> --- a/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c
> +++ b/drivers/pinctrl/bcm/pinctrl-nsp-gpio.c
> @@ -439,7 +439,8 @@ static int nsp_gpio_set_strength(struct nsp_gpio *chip, unsigned gpio,
> static int nsp_gpio_get_strength(struct nsp_gpio *chip, unsigned gpio,
> u16 *strength)
> {
> - unsigned int i, offset, shift;
> + unsigned int offset, shift;
> + int i;
> u32 val;
> unsigned long flags;
>
>

The fix is a valid fix. And at the same time it exposes other potential
issues in the driver. I just found the loop used in _set_strength and
_get_strength is inconsistent:

In _set_strength:

427 for (i = GPIO_DRV_STRENGTH_BITS; i > 0; i--) {

For i to start at GPIO_DRV_STRENGTH_BITS, it seems to be wrong.

428 val = readl(chip->io_ctrl + offset);
429 val &= ~BIT(shift);
430 val |= ((strength >> (i-1)) & 0x1) << shift;
431 writel(val, chip->io_ctrl + offset);
432 offset += 4;
433 }

In _get_strength:

451 for (i = (GPIO_DRV_STRENGTH_BITS - 1); i >= 0; i--) {
452 val = readl(chip->io_ctrl + offset) & BIT(shift);
453 val >>= shift;
454 *strength += (val << i);
455 offset += 4;
456 }

Reddy, could you please review and comment?

Thanks,

Ray




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