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Message-ID: <CA+J-oUtxiQBOT+VM3fbOUM8HL5TX-C4HqtbbT__b4_KsGAJy1w@mail.gmail.com>
Date: Fri, 22 Sep 2023 10:39:13 -0400
From: Jian Zhang <zhangjian.3032@...edance.com>
To: Joel Stanley <joel@....id.au>
Cc: Tommy Huang <tommy_huang@...eedtech.com>,
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: [External] Re: [PATCH] i2c: aspeed: Fix i2c bus hang in slave read
> From: "Joel Stanley"<joel@....id.au>
> Date: Fri, Sep 22, 2023, 14:48
> Subject: [External] Re: [PATCH] i2c: aspeed: Fix i2c bus hang in slave read
> 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>
> 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?
I feel it's for solving the same issue, but I think this patch is
missing the action
`bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;`,
which means it can't resolve my problem. @Tommy, can you help confirm this?
Thanks,
Jian
>
> 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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