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(-)
--- 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; }