This is a note to let you know that I've just added the patch titled
gpio: pca953x: Improve interrupt support
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpio-pca953x-improve-interrupt-support.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b5a90e902e44995e78a04c3cedf2a819040bc098
Author: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
Date: Thu Jun 6 15:31:02 2024 +1200
gpio: pca953x: Improve interrupt support
[ Upstream commit d6179f6c6204f9932aed3a7a2100b4a295dfed9d ]
The GPIO drivers with latch interrupt support (typically types starting
with PCAL) have interrupt status registers to determine which particular
inputs have caused an interrupt. Unfortunately there is no atomic
operation to read these registers and clear the interrupt. Clearing the
interrupt is done by reading the input registers.
The code was reading the interrupt status registers, and then reading
the input registers. If an input changed between these two events it was
lost.
The solution in this patch is to revert to the non-latch version of
code, i.e. remembering the previous input status, and looking for the
changes. This system results in no more I2C transfers, so is no slower.
The latch property of the device still means interrupts will still be
noticed if the input changes back to its initial state.
Fixes: 44896beae605 ("gpio: pca953x: add PCAL9535 interrupt support for Galileo Gen2")
Signed-off-by: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240606033102.2271916-1-mark.tomlinson@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 4860bf3b7e002..45f3836c4f0fa 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -733,25 +733,6 @@ static bool pca953x_irq_pending(struct pca953x_chip *chip, unsigned long *pendin
DECLARE_BITMAP(trigger, MAX_LINE);
int ret;
- if (chip->driver_data & PCA_PCAL) {
- /* Read the current interrupt status from the device */
- ret = pca953x_read_regs(chip, PCAL953X_INT_STAT, trigger);
- if (ret)
- return false;
-
- /* Check latched inputs and clear interrupt status */
- ret = pca953x_read_regs(chip, chip->regs->input, cur_stat);
- if (ret)
- return false;
-
- /* Apply filter for rising/falling edge selection */
- bitmap_replace(new_stat, chip->irq_trig_fall, chip->irq_trig_raise, cur_stat, gc->ngpio);
-
- bitmap_and(pending, new_stat, trigger, gc->ngpio);
-
- return !bitmap_empty(pending, gc->ngpio);
- }
-
ret = pca953x_read_regs(chip, chip->regs->input, cur_stat);
if (ret)
return false;
