Re: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition.

Wolfram Sang
2020-04-29T07:54:02Z

[-- Attachment #1: Type: text/plain, Size: 1667 bytes --]

On Wed, Apr 29, 2020 at 11:37:37AM +0800, ryan_chen wrote:
> 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.
>
> Signed-off-by: ryan_chen <ryan_chen@aspeedtech.com>

v0? is it a prototype?

And is there maybe a Fixes: tag for it?

> ---
> drivers/i2c/busses/i2c-aspeed.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index 07c1993274c5..f51702d86a90 100644
> --- 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(int irq, void *dev_id)
> /* 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(int irq, void *dev_id)
> 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;
> }
> --
> 2.17.1
>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]