From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: ryan_chen <ryan_chen@aspeedtech.com>,
Brendan Higgins <brendanhiggins@google.com>,
Joel Stanley <joel@jms.id.au>, Andrew Jeffery <andrew@aj.id.au>,
linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition.
Date: Thu, 30 Apr 2020 20:52:56 +1000 [thread overview]
Message-ID: <9b5fbaf29adccc5abb66c3d39ecc92a2d5f10d10.camel@kernel.crashing.org> (raw)
In-Reply-To: <20200429033737.2781-1-ryan_chen@aspeedtech.com>
On Wed, 2020-04-29 at 11:37 +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>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
--
> ---
> 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;
> }
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next prev parent reply other threads:[~2020-04-30 10:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 3:37 [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition ryan_chen
2020-04-29 7:53 ` Wolfram Sang
2020-04-29 8:12 ` Ryan Chen
2020-04-29 9:03 ` Wolfram Sang
2020-04-30 10:55 ` Benjamin Herrenschmidt
2020-05-05 1:52 ` Ryan Chen
2020-04-30 10:52 ` Benjamin Herrenschmidt [this message]
2020-04-30 14:17 ` Wolfram Sang
2020-05-05 1:51 ` Ryan Chen
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