[PATCH] GPIO, Fix bug where the wrong GPIO register is written to

From: Paul Thomas
Date: Sat Jan 25 2020 - 17:15:46 EST


Care is taken with "index", however with the current version
the actual xgpio_writereg is using index for data but
xgpio_regoffset(chip, i) for the offset. And since i is already
incremented it is incorrect. This patch fixes it so that index
is used for the offset too.

Signed-off-by: Paul Thomas <pthomas8589@xxxxxxxxx>
---
There are many different ways to correct this, I'd just like it to get
fixed. I've tested this with a 5.2 kernel, but this patch is against
5.5rc7.

drivers/gpio/gpio-xilinx.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index a9748b5198e6..67f9f82e0db0 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -147,9 +147,10 @@ static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
for (i = 0; i < gc->ngpio; i++) {
if (*mask == 0)
break;
+ /* Once finished with an index write it out to the register */
if (index != xgpio_index(chip, i)) {
xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
- xgpio_regoffset(chip, i),
+ index * XGPIO_CHANNEL_OFFSET,
chip->gpio_state[index]);
spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
index = xgpio_index(chip, i);
@@ -165,7 +166,7 @@ static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
}

xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
- xgpio_regoffset(chip, i), chip->gpio_state[index]);
+ index * XGPIO_CHANNEL_OFFSET, chip->gpio_state[index]);

spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
}
--
2.17.1