linux-kernel - [PATCH v1] gpio: pca953x: Reduce stack usage in couple of functions

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Date:   Wed, 23 Oct 2019 18:30:56 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        linux-gpio@...r.kernel.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Yury Norov <yury.norov@...il.com>,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1] gpio: pca953x: Reduce stack usage in couple of functions

Simple bitmap operations are safe against in-place modifications.
Due to above we may get rid of temporary variables in some cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---

Andrew, it can be folded into "gpio: pca953x: Convert to use bitmap API"

 drivers/gpio/gpio-pca953x.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index f80ed5a43614..b9e326dfed23 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -468,7 +468,6 @@ static void pca953x_gpio_set_multiple(struct gpio_chip *gc,
 {
 	struct pca953x_chip *chip = gpiochip_get_data(gc);
 	DECLARE_BITMAP(reg_val, MAX_LINE);
-	DECLARE_BITMAP(new_val, MAX_LINE);
 	int ret;
 
 	mutex_lock(&chip->i2c_lock);
@@ -476,9 +475,9 @@ static void pca953x_gpio_set_multiple(struct gpio_chip *gc,
 	if (ret)
 		goto exit;
 
-	bitmap_replace(new_val, reg_val, bits, mask, gc->ngpio);
+	bitmap_replace(reg_val, reg_val, bits, mask, gc->ngpio);
 
-	pca953x_write_regs(chip, chip->regs->output, new_val);
+	pca953x_write_regs(chip, chip->regs->output, reg_val);
 exit:
 	mutex_unlock(&chip->i2c_lock);
 }
@@ -605,7 +604,6 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 	struct pca953x_chip *chip = gpiochip_get_data(gc);
 	DECLARE_BITMAP(irq_mask, MAX_LINE);
 	DECLARE_BITMAP(reg_direction, MAX_LINE);
-	DECLARE_BITMAP(new_irqs, MAX_LINE);
 	int level;
 
 	pca953x_read_regs(chip, chip->regs->direction, reg_direction);
@@ -620,8 +618,8 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 		pca953x_write_regs(chip, PCAL953X_INT_MASK, irq_mask);
 	}
 
-	bitmap_or(new_irqs, chip->irq_trig_fall, chip->irq_trig_raise, gc->ngpio);
-	bitmap_and(irq_mask, new_irqs, reg_direction, gc->ngpio);
+	bitmap_or(irq_mask, chip->irq_trig_fall, chip->irq_trig_raise, gc->ngpio);
+	bitmap_and(irq_mask, irq_mask, reg_direction, gc->ngpio);
 
 	/* Look for any newly setup interrupt */
 	for_each_set_bit(level, irq_mask, gc->ngpio)
-- 
2.23.0