linux-kernel - Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave

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Date:   Mon, 7 Jun 2021 15:57:22 +0100
From:   Graeme Gregory <graeme@...iainc.com>
To:     Quan Nguyen <quan@...amperecomputing.com>
Cc:     Corey Minyard <minyard@....org>, Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Wolfram Sang <wsa@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        openipmi-developer@...ts.sourceforge.net,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org,
        Open Source Submission <patches@...erecomputing.com>,
        "Thang Q . Nguyen" <thang@...amperecomputing.com>,
        Phong Vo <phong@...amperecomputing.com>,
        openbmc@...ts.ozlabs.org
Subject: Re: [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy()

On Wed, May 19, 2021 at 02:49:32PM +0700, Quan Nguyen wrote:
> 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@...amperecomputing.com>
> ---
> 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);

This as far as I can see is still a recursive spinlock, and the spinlock
debugger seems to agree with me.

Graeme

> +
> +	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
>