linux-kernel - Re: [PATCH 8/9] soundwire: intel: add wake interrupt support

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Date:   Tue, 30 Jun 2020 22:21:26 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        rander.wang@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
        hui.wang@...onical.com, pierre-louis.bossart@...ux.intel.com,
        sanyog.r.kale@...el.com, slawomir.blauciak@...el.com,
        mengdong.lin@...el.com, bard.liao@...el.com
Subject: Re: [PATCH 8/9] soundwire: intel: add wake interrupt support

On 24-06-20, 01:35, Bard Liao wrote:
> From: Rander Wang <rander.wang@...el.com>
> 
> When system is suspended in clock stop mode on intel platforms, both
> master and slave are in clock stop mode and soundwire bus is taken
> over by a glue hardware. The bus message for jack event is processed
> by this glue hardware, which will trigger an interrupt to resume audio
> pci device. Then audio pci driver will resume soundwire master and slave,
> transfer bus ownership to master, finally slave will report jack event
> to master and codec driver is triggered to check jack status.
> 
> if a slave has been attached to a bus, the slave->dev_num_sticky
> should be non-zero, so we can check this value to skip the
> ghost devices defined in ACPI table but not populated in hardware.
> 
> Signed-off-by: Rander Wang <rander.wang@...el.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> ---
>  drivers/soundwire/intel.c      | 48 +++++++++++++++++++++++++++++++++-
>  drivers/soundwire/intel.h      |  1 +
>  drivers/soundwire/intel_init.c | 22 ++++++++++++++++
>  3 files changed, 70 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> index 06c553d94890..22d9fd3e34fa 100644
> --- a/drivers/soundwire/intel.c
> +++ b/drivers/soundwire/intel.c
> @@ -13,6 +13,7 @@
>  #include <linux/io.h>
>  #include <linux/platform_device.h>
>  #include <sound/pcm_params.h>
> +#include <linux/pm_runtime.h>
>  #include <sound/soc.h>
>  #include <linux/soundwire/sdw_registers.h>
>  #include <linux/soundwire/sdw.h>
> @@ -436,7 +437,7 @@ static int intel_shim_init(struct sdw_intel *sdw, bool clock_stop)
>  	return ret;
>  }
>  
> -static void __maybe_unused intel_shim_wake(struct sdw_intel *sdw, bool wake_enable)
> +static void intel_shim_wake(struct sdw_intel *sdw, bool wake_enable)

why drop __maybe?

>  {
>  	void __iomem *shim = sdw->link_res->shim;
>  	unsigned int link_id = sdw->instance;
> @@ -1337,6 +1338,51 @@ static int intel_master_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +int intel_master_process_wakeen_event(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct sdw_intel *sdw;
> +	struct sdw_bus *bus;
> +	struct sdw_slave *slave;
> +	void __iomem *shim;
> +	u16 wake_sts;
> +
> +	sdw = platform_get_drvdata(pdev);
> +	bus = &sdw->cdns.bus;
> +
> +	if (bus->prop.hw_disabled) {
> +		dev_dbg(dev,
> +			"SoundWire master %d is disabled, ignoring\n",
> +			bus->link_id);

single line pls

> +		return 0;
> +	}
> +
> +	shim = sdw->link_res->shim;
> +	wake_sts = intel_readw(shim, SDW_SHIM_WAKESTS);
> +
> +	if (!(wake_sts & BIT(sdw->instance)))
> +		return 0;
> +
> +	/* disable WAKEEN interrupt ASAP to prevent interrupt flood */
> +	intel_shim_wake(sdw, false);

when & where is this enabled?

> +
> +	/*
> +	 * wake up master and slave so that slave can notify master
> +	 * the wakeen event and let codec driver check codec status
> +	 */
> +	list_for_each_entry(slave, &bus->slaves, node) {
> +		/*
> +		 * discard devices that are defined in ACPI tables but
> +		 * not physically present and devices that cannot
> +		 * generate wakes
> +		 */
> +		if (slave->dev_num_sticky && slave->prop.wake_capable)
> +			pm_request_resume(&slave->dev);

Hmmm, shouldn't slave do this? would it not make sense to notify the
slave thru callback and then slave decides to resume or not..? 

-- 
~Vinod