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    SubjectRe: [PATCH v2 9/9] gpio: pci-idio-16: make use of raw_spinlock variants
    On Tue, Mar 21, 2017 at 05:43:09PM -0500, Julia Cartwright wrote:
    >The pci-idio-16 gpio driver currently implements an irq_chip for handling
    >interrupts; due to how irq_chip handling is done, it's necessary for the
    >irq_chip methods to be invoked from hardirq context, even on a a
    >real-time kernel. Because the spinlock_t type becomes a "sleeping"
    >spinlock w/ RT kernels, it is not suitable to be used with irq_chips.
    >
    >A quick audit of the operations under the lock reveal that they do only
    >minimal, bounded work, and are therefore safe to do under a raw spinlock.
    >
    >Signed-off-by: Julia Cartwright <julia@ni.com>

    Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>

    >---
    >New patch as of v2 of series.
    >
    > drivers/gpio/gpio-pci-idio-16.c | 28 ++++++++++++++--------------
    > 1 file changed, 14 insertions(+), 14 deletions(-)
    >
    >diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c
    >index 269ab628634b..7de4f6a2cb49 100644
    >--- a/drivers/gpio/gpio-pci-idio-16.c
    >+++ b/drivers/gpio/gpio-pci-idio-16.c
    >@@ -59,7 +59,7 @@ struct idio_16_gpio_reg {
    > */
    > struct idio_16_gpio {
    > struct gpio_chip chip;
    >- spinlock_t lock;
    >+ raw_spinlock_t lock;
    > struct idio_16_gpio_reg __iomem *reg;
    > unsigned long irq_mask;
    > };
    >@@ -121,7 +121,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,
    > } else
    > base = &idio16gpio->reg->out0_7;
    >
    >- spin_lock_irqsave(&idio16gpio->lock, flags);
    >+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);
    >
    > if (value)
    > out_state = ioread8(base) | mask;
    >@@ -130,7 +130,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,
    >
    > iowrite8(out_state, base);
    >
    >- spin_unlock_irqrestore(&idio16gpio->lock, flags);
    >+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
    > }
    >
    > static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
    >@@ -140,7 +140,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
    > unsigned long flags;
    > unsigned int out_state;
    >
    >- spin_lock_irqsave(&idio16gpio->lock, flags);
    >+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);
    >
    > /* process output lines 0-7 */
    > if (*mask & 0xFF) {
    >@@ -160,7 +160,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
    > iowrite8(out_state, &idio16gpio->reg->out8_15);
    > }
    >
    >- spin_unlock_irqrestore(&idio16gpio->lock, flags);
    >+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
    > }
    >
    > static void idio_16_irq_ack(struct irq_data *data)
    >@@ -177,11 +177,11 @@ static void idio_16_irq_mask(struct irq_data *data)
    > idio16gpio->irq_mask &= ~mask;
    >
    > if (!idio16gpio->irq_mask) {
    >- spin_lock_irqsave(&idio16gpio->lock, flags);
    >+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);
    >
    > iowrite8(0, &idio16gpio->reg->irq_ctl);
    >
    >- spin_unlock_irqrestore(&idio16gpio->lock, flags);
    >+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
    > }
    > }
    >
    >@@ -196,11 +196,11 @@ static void idio_16_irq_unmask(struct irq_data *data)
    > idio16gpio->irq_mask |= mask;
    >
    > if (!prev_irq_mask) {
    >- spin_lock_irqsave(&idio16gpio->lock, flags);
    >+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);
    >
    > ioread8(&idio16gpio->reg->irq_ctl);
    >
    >- spin_unlock_irqrestore(&idio16gpio->lock, flags);
    >+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
    > }
    > }
    >
    >@@ -229,11 +229,11 @@ static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
    > struct gpio_chip *const chip = &idio16gpio->chip;
    > int gpio;
    >
    >- spin_lock(&idio16gpio->lock);
    >+ raw_spin_lock(&idio16gpio->lock);
    >
    > irq_status = ioread8(&idio16gpio->reg->irq_status);
    >
    >- spin_unlock(&idio16gpio->lock);
    >+ raw_spin_unlock(&idio16gpio->lock);
    >
    > /* Make sure our device generated IRQ */
    > if (!(irq_status & 0x3) || !(irq_status & 0x4))
    >@@ -242,12 +242,12 @@ static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
    > for_each_set_bit(gpio, &idio16gpio->irq_mask, chip->ngpio)
    > generic_handle_irq(irq_find_mapping(chip->irqdomain, gpio));
    >
    >- spin_lock(&idio16gpio->lock);
    >+ raw_spin_lock(&idio16gpio->lock);
    >
    > /* Clear interrupt */
    > iowrite8(0, &idio16gpio->reg->in0_7);
    >
    >- spin_unlock(&idio16gpio->lock);
    >+ raw_spin_unlock(&idio16gpio->lock);
    >
    > return IRQ_HANDLED;
    > }
    >@@ -302,7 +302,7 @@ static int idio_16_probe(struct pci_dev *pdev, const struct pci_device_id *id)
    > idio16gpio->chip.set = idio_16_gpio_set;
    > idio16gpio->chip.set_multiple = idio_16_gpio_set_multiple;
    >
    >- spin_lock_init(&idio16gpio->lock);
    >+ raw_spin_lock_init(&idio16gpio->lock);
    >
    > err = devm_gpiochip_add_data(dev, &idio16gpio->chip, idio16gpio);
    > if (err) {
    >--
    >2.12.0
    >

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