diff mbox series

[5.4,49/57] i2c: aspeed: Avoid i2c interrupt status clear race condition.

Message ID 20200504165500.835261420@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman May 4, 2020, 5:57 p.m. UTC 
From: ryan_chen <ryan_chen@aspeedtech.com>

commit c926c87b8e36dcc0ea5c2a0a0227ed4f32d0516a upstream.

In AST2600 there have a slow peripheral bus between CPU and i2c
controller. Therefore GIC i2c interrupt status clear have delay timing,
when CPU issue write clear i2c controller interrupt status. To avoid
this issue, the driver need have read after write clear at i2c ISR.

Fixes: f327c686d3ba ("i2c: aspeed: added driver for Aspeed I2C")
Signed-off-by: ryan_chen <ryan_chen@aspeedtech.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[wsa: added Fixes tag]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-aspeed.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -603,6 +603,7 @@  static irqreturn_t aspeed_i2c_bus_irq(in
 	/* Ack all interrupts except for Rx done */
 	writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
 	       bus->base + ASPEED_I2C_INTR_STS_REG);
+	readl(bus->base + ASPEED_I2C_INTR_STS_REG);
 	irq_remaining = irq_received;
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
@@ -645,9 +646,11 @@  static irqreturn_t aspeed_i2c_bus_irq(in
 			irq_received, irq_handled);
 
 	/* Ack Rx done */
-	if (irq_received & ASPEED_I2CD_INTR_RX_DONE)
+	if (irq_received & ASPEED_I2CD_INTR_RX_DONE) {
 		writel(ASPEED_I2CD_INTR_RX_DONE,
 		       bus->base + ASPEED_I2C_INTR_STS_REG);
+		readl(bus->base + ASPEED_I2C_INTR_STS_REG);
+	}
 	spin_unlock(&bus->lock);
 	return irq_remaining ? IRQ_NONE : IRQ_HANDLED;
 }