3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Mika Westerberg mika.westerberg@linux.intel.com
commit 39ce8150a079e3ae6ed9abf26d7918a558ef7c19 upstream.
There is a hardware issue in Intel Baytrail where concurrent GPIO register access might result reads of 0xffffffff and writes might get dropped completely.
Prevent this from happening by taking the serializing lock in all places where it is possible that more than one thread might be accessing the hardware concurrently.
Signed-off-by: Mika Westerberg mika.westerberg@linux.intel.com Signed-off-by: Linus Walleij linus.walleij@linaro.org [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/pinctrl/pinctrl-baytrail.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)
--- a/drivers/pinctrl/pinctrl-baytrail.c +++ b/drivers/pinctrl/pinctrl-baytrail.c @@ -194,6 +194,9 @@ static int byt_gpio_request(struct gpio_ struct byt_gpio *vg = to_byt_gpio(chip); void __iomem *reg = byt_gpio_reg(chip, offset, BYT_CONF0_REG); u32 value, gpio_mux; + unsigned long flags; + + spin_lock_irqsave(&vg->lock, flags);
/* * In most cases, func pin mux 000 means GPIO function. @@ -207,18 +210,16 @@ static int byt_gpio_request(struct gpio_ value = readl(reg) & BYT_PIN_MUX; gpio_mux = byt_get_gpio_mux(vg, offset); if (WARN_ON(gpio_mux != value)) { - unsigned long flags; - - spin_lock_irqsave(&vg->lock, flags); value = readl(reg) & ~BYT_PIN_MUX; value |= gpio_mux; writel(value, reg); - spin_unlock_irqrestore(&vg->lock, flags);
dev_warn(&vg->pdev->dev, "pin %u forcibly re-configured as GPIO\n", offset); }
+ spin_unlock_irqrestore(&vg->lock, flags); + pm_runtime_get(&vg->pdev->dev);
return 0; @@ -266,7 +267,15 @@ static int byt_irq_type(struct irq_data static int byt_gpio_get(struct gpio_chip *chip, unsigned offset) { void __iomem *reg = byt_gpio_reg(chip, offset, BYT_VAL_REG); - return readl(reg) & BYT_LEVEL; + struct byt_gpio *vg = to_byt_gpio(chip); + unsigned long flags; + u32 val; + + spin_lock_irqsave(&vg->lock, flags); + val = readl(reg); + spin_unlock_irqrestore(&vg->lock, flags); + + return val & BYT_LEVEL; }
static void byt_gpio_set(struct gpio_chip *chip, unsigned offset, int value) @@ -435,8 +444,10 @@ static void byt_irq_ack(struct irq_data unsigned offset = irqd_to_hwirq(d); void __iomem *reg;
+ spin_lock(&vg->lock); reg = byt_gpio_reg(&vg->chip, offset, BYT_INT_STAT_REG); writel(BIT(offset % 32), reg); + spin_unlock(&vg->lock); }
static void byt_irq_unmask(struct irq_data *d)