linux-kernel - Re: [PATCH 01/10] soundwire: bus: Allow SoundWire peripherals to register IRQ handlers

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Message-ID: <0471f085-14bf-c159-9b92-62983af6c19a@linux.intel.com>
Date:   Fri, 12 May 2023 08:45:51 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>, broonie@...nel.org,
        lee@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        tglx@...utronix.de, maz@...nel.org, linus.walleij@...aro.org,
        vkoul@...nel.org
Cc:     lgirdwood@...il.com, yung-chuan.liao@...ux.intel.com,
        sanyog.r.kale@...el.com, alsa-devel@...a-project.org,
        patches@...nsource.cirrus.com, devicetree@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/10] soundwire: bus: Allow SoundWire peripherals to
 register IRQ handlers




> @@ -1711,6 +1739,9 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
>  				struct device *dev = &slave->dev;
>  				struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
>  
> +				if (slave->prop.use_domain_irq && slave->irq)
> +					handle_nested_irq(slave->irq);
> +

I am a bit lost here, I can understand that alerts would be handled by a
dedicated handler, but here the code continues and will call the
existing interrupt_callback.

Is this intentional? I wonder if there's a risk with two entities
dealing with the same event and programming the same registers.
Shouldn't there be some sort of 'either or' rule?

>  				if (drv->ops && drv->ops->interrupt_callback) {
>  					slave_intr.sdca_cascade = sdca_cascade;
>  					slave_intr.control_port = clear;
> diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
> index 1f43ee848eac8..fafbc284e82da 100644
> --- a/drivers/soundwire/bus_type.c
> +++ b/drivers/soundwire/bus_type.c
> @@ -122,6 +122,12 @@ static int sdw_drv_probe(struct device *dev)
>  	if (drv->ops && drv->ops->read_prop)
>  		drv->ops->read_prop(slave);
>  
> +	if (slave->prop.use_domain_irq) {
> +		slave->irq = irq_create_mapping(slave->bus->domain, slave->dev_num);
> +		if (!slave->irq)
> +			dev_warn(dev, "Failed to map IRQ\n");
> +	}
> +
>  	/* init the sysfs as we have properties now */
>  	ret = sdw_slave_sysfs_init(slave);
>  	if (ret < 0)
> @@ -166,7 +172,13 @@ static int sdw_drv_remove(struct device *dev)
>  	int ret = 0;
>  
>  	mutex_lock(&slave->sdw_dev_lock);
> +
>  	slave->probed = false;
> +
> +	if (slave->prop.use_domain_irq)
> +		irq_dispose_mapping(irq_find_mapping(slave->bus->domain,
> +						     slave->dev_num));
> +
>  	mutex_unlock(&slave->sdw_dev_lock);
>  
>  	if (drv->remove)
> diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
> index ef645de13ae93..c3ab5e5f9cfa4 100644
> --- a/include/linux/soundwire/sdw.h
> +++ b/include/linux/soundwire/sdw.h
> @@ -5,6 +5,8 @@
>  #define __SOUNDWIRE_H
>  
>  #include <linux/bug.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/bitfield.h>
>  
> @@ -369,6 +371,7 @@ struct sdw_dpn_prop {
>   * @clock_reg_supported: the Peripheral implements the clock base and scale
>   * registers introduced with the SoundWire 1.2 specification. SDCA devices
>   * do not need to set this boolean property as the registers are required.
> + * @use_domain_irq: call actual IRQ handler on slave, as well as callback

what callback, the interrupt_callback? That would mean the interrupt is
handled twice?

I am probably missing something here?

>   */
>  struct sdw_slave_prop {
>  	u32 mipi_revision;
> @@ -393,6 +396,7 @@ struct sdw_slave_prop {
>  	u8 scp_int1_mask;
>  	u32 quirks;
>  	bool clock_reg_supported;
> +	bool use_domain_irq;
>  };