Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()

[Quan Nguyen]

On 21/05/2021 13:09, Ryan Chen wrote:
> > -----Original Message-----
> > From: Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>
> > Sent: Thursday, May 20, 2021 10:10 PM
> > To: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>; Corey Minyard
> > <minyard@xxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Joel Stanley
> > <joel@xxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>; Brendan Higgins
> > <brendanhiggins@xxxxxxxxxx>; Benjamin Herrenschmidt
> > <benh@xxxxxxxxxxxxxxxxxxx>; Wolfram Sang <wsa@xxxxxxxxxx>; Philipp Zabel
> > <p.zabel@xxxxxxxxxxxxxx>; openipmi-developer@xxxxxxxxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux-aspeed@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linux-i2c@xxxxxxxxxxxxxxx
> > Cc: Open Source Submission <patches@xxxxxxxxxxxxxxxxxxx>; Thang Q .
> > Nguyen <thang@xxxxxxxxxxxxxxxxxxxxxx>; Phong Vo
> > <phong@xxxxxxxxxxxxxxxxxxxxxx>; openbmc@xxxxxxxxxxxxxxxx
> > Subject: Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()
> >
> > On 20/05/2021 18:06, Ryan Chen wrote:
> > > > -----Original Message-----
> > > > From: openbmc
> > > > <openbmc-bounces+ryan_chen=aspeedtech.com@xxxxxxxxxxxxxxxx> On
> > Behalf
> > > > Of Quan Nguyen
> > > > Sent: Wednesday, May 19, 2021 3:50 PM
> > > > To: Corey Minyard <minyard@xxxxxxx>; Rob Herring
> > > > <robh+dt@xxxxxxxxxx>; Joel Stanley <joel@xxxxxxxxx>; Andrew Jeffery
> > > > <andrew@xxxxxxxx>; Brendan Higgins <brendanhiggins@xxxxxxxxxx>;
> > > > Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>; Wolfram Sang
> > > > <wsa@xxxxxxxxxx>; Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>;
> > > > openipmi-developer@xxxxxxxxxxxxxxxxxxxxx;
> > > > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > > > linux-aspeed@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > > linux-i2c@xxxxxxxxxxxxxxx
> > > > Cc: Open Source Submission <patches@xxxxxxxxxxxxxxxxxxx>; Thang Q .
> > > > Nguyen <thang@xxxxxxxxxxxxxxxxxxxxxx>; Phong Vo
> > > > <phong@xxxxxxxxxxxxxxxxxxxxxx>; openbmc@xxxxxxxxxxxxxxxx
> > > > Subject: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()
> > > >
> > > > Slave i2c device on AST2500 received a lot of slave irq while it is
> > > > busy processing the response. To handle this case, adds and exports
> > > > aspeed_set_slave_busy() for controller to temporary stop slave irq
> > > > while slave is handling the response, and re-enable them again when the
> > response is ready.
> > > > Signed-off-by: Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > > v3:
> > > >     + First introduce in v3 [Quan]
> > > >
> > > >    drivers/i2c/busses/i2c-aspeed.c | 20 ++++++++++++++++++++
> > > >    1 file changed, 20 insertions(+)
> > > >
> > > > diff --git a/drivers/i2c/busses/i2c-aspeed.c
> > > > b/drivers/i2c/busses/i2c-aspeed.c index b2e9c8f0ddf7..9926d04831a2
> > > > 100644
> > > > --- a/drivers/i2c/busses/i2c-aspeed.c
> > > > +++ b/drivers/i2c/busses/i2c-aspeed.c
> > > > @@ -944,6 +944,26 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus
> > > > *bus,
> > > >    	return 0;
> > > >    }
> > > >
> > > > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > > > +void aspeed_set_slave_busy(struct i2c_adapter *adap, bool busy) {
> > > > +	struct aspeed_i2c_bus *bus = i2c_get_adapdata(adap);
> > > > +	unsigned long current_mask, flags;
> > > > +
> > > > +	spin_lock_irqsave(&bus->lock, flags);
> > > > +
> > > > +	current_mask = readl(bus->base + ASPEED_I2C_INTR_CTRL_REG);
> > > > +	if (busy)
> > > > +		current_mask &= ~(ASPEED_I2CD_INTR_RX_DONE |
> > > > ASPEED_I2CD_INTR_SLAVE_MATCH);
> > > > +	else
> > > > +		current_mask |= ASPEED_I2CD_INTR_RX_DONE |
> > > > ASPEED_I2CD_INTR_SLAVE_MATCH;
> > > > +	writel(current_mask, bus->base + ASPEED_I2C_INTR_CTRL_REG);
> > > > +
> > > > +	spin_unlock_irqrestore(&bus->lock, flags); }
> > > > +EXPORT_SYMBOL_GPL(aspeed_set_slave_busy);
> > > > +#endif
> > > > +
> > > >    static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus)  {
> > > >    	struct platform_device *pdev = to_platform_device(bus->dev);
> > > > --
> > > > 2.28.0
> > >
> > > Hello,
> > > 	The better idea is use disable i2c slave mode.
> > > 	Due to if i2c controller running in slave will get slave match, and latch the
> > SCL.
> > > 	Until cpu clear interrupt status.
> > > Ryan
> > Thanks Ryan,
> >
> > Do you mean to enable/disable slave function as per example code below ?
> Yes. it is.

Dear Ryan,

This solution looks good. I'll switch to use this way in next version.
Thanks for the suggestion.

- Quan

> >           /* Turn on slave mode. */
> >           func_ctrl_reg_val = readl(bus->base +
> > ASPEED_I2C_FUN_CTRL_REG);
> >           func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
> >           writel(func_ctrl_reg_val, bus->base +
> > ASPEED_I2C_FUN_CTRL_REG);
> >
> > Will try this idea.
> > - Quan