On 12/24/2015 4:05 AM, Ray Jui wrote:

+ Reddy

On 12/23/2015 2:37 AM, Andrzej Hajda wrote:

quoted

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 <redacted>
---
  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?

Hi Ray,

             The logic is correct. The drive strength has three bits distributed in three registers. In one case the "-1" is in for loop initialization and the other case it is in the for loop body. The fix looks good.

Thanks
Dhananjay

Thanks,

Ray