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Message-ID: <CACPK8XfWKLS_4nBC+NCSw=21iQeaHzBXOROmz9T+S0qZHCBKeg@mail.gmail.com>
Date: Fri, 22 Sep 2023 06:47:43 +0000
From: Joel Stanley <joel@....id.au>
To: Jian Zhang <zhangjian.3032@...edance.com>,
Tommy Huang <tommy_huang@...eedtech.com>
Cc: brendan.higgins@...ux.dev, benh@...nel.crashing.org,
andrew@...id.au, zhangjian3032@...il.com, yulei.sh@...edance.com,
xiexinnan@...edance.com,
"open list:ARM/ASPEED I2C DRIVER" <linux-i2c@...r.kernel.org>,
"moderated list:ARM/ASPEED I2C DRIVER" <openbmc@...ts.ozlabs.org>,
"moderated list:ARM/ASPEED MACHINE SUPPORT"
<linux-arm-kernel@...ts.infradead.org>,
"moderated list:ARM/ASPEED MACHINE SUPPORT"
<linux-aspeed@...ts.ozlabs.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: aspeed: Fix i2c bus hang in slave read
On Thu, 10 Aug 2023 at 07:22, Jian Zhang <zhangjian.3032@...edance.com> wrote:
>
> When the `CONFIG_I2C_SLAVE` option is enabled and the device operates
> as a slave, a situation arises where the master sends a START signal
> without the accompanying STOP signal. This action results in a
> persistent I2C bus timeout. The core issue stems from the fact that
> the i2c controller remains in a slave read state without a timeout
> mechanism. As a consequence, the bus perpetually experiences timeouts.
>
> This proposed patch addresses this problem by introducing a status
> check during i2c transmit timeouts. In the event that the controller
> is in a slave read state, the i2c controller will be reset to restore
> proper functionality and allow the I2C bus to resume normal operation.
>
> Signed-off-by: Jian Zhang <zhangjian.3032@...edance.com>
Tommy has submitted a similar fix:
https://lore.kernel.org/linux-i2c/20230906004910.4157305-1-tommy_huang@aspeedtech.com/
His change is very heavy handed; it reinitialises the bus including
re-parsing the device tree (!).
Should we have merged this fix instead? If not, are you able to
confirm that his change fixes your issue?
Cheers,
Joel
> ---
> drivers/i2c/busses/i2c-aspeed.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index e76befe3f60f..1a95205fc946 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -113,6 +113,7 @@
> ASPEED_I2CD_M_RX_CMD | \
> ASPEED_I2CD_M_TX_CMD | \
> ASPEED_I2CD_M_START_CMD)
> +#define ASPEED_I2CD_SLAVE_CMDS_MASK GENMASK(31, 29)
>
> /* 0x18 : I2CD Slave Device Address Register */
> #define ASPEED_I2CD_DEV_ADDR_MASK GENMASK(6, 0)
> @@ -706,6 +707,22 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
> ASPEED_I2CD_BUS_BUSY_STS))
> aspeed_i2c_recover_bus(bus);
>
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + /*
> + * If master timed out and bus is in slave mode.
> + * reset the slave mode.
> + */
> + if (readl(bus->base + ASPEED_I2C_CMD_REG) & ASPEED_I2CD_SLAVE_CMDS_MASK) {
> + spin_lock_irqsave(&bus->lock, flags);
> + u32 func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
> +
> + writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
> + writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
> + bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
> + spin_unlock_irqrestore(&bus->lock, flags);
> + }
> +#endif
> +
> /*
> * If timed out and the state is still pending, drop the pending
> * master command.
> --
> 2.30.2
>
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