[alsa-devel] [RFC PATCH 28/40] soundwire: intel: handle disabled links

[Sanyog Kale]

On Thu, Jul 25, 2019 at 06:40:20PM -0500, Pierre-Louis Bossart wrote:
> On most hardware platforms, SoundWire interfaces are pin-muxed with
> other interfaces (typically DMIC or I2S) and the status of each link
> needs to be checked at boot time.
> 
> For Intel platforms, the BIOS provides a menu to enable/disable the
> links separately, and the information is provided to the OS with an
> Intel-specific _DSD property. The same capability will be added to
> revisions of the MIPI DisCo specification.
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> ---
>  drivers/soundwire/intel.c     | 26 ++++++++++++++++++++++----
>  include/linux/soundwire/sdw.h |  2 ++
>  2 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> index 796ac2bc8cea..5947fa8e840b 100644
> --- a/drivers/soundwire/intel.c
> +++ b/drivers/soundwire/intel.c
> @@ -90,6 +90,8 @@
>  #define SDW_ALH_STRMZCFG_DMAT		GENMASK(7, 0)
>  #define SDW_ALH_STRMZCFG_CHN		GENMASK(19, 16)
>  
> +#define SDW_INTEL_QUIRK_MASK_BUS_DISABLE	BIT(1)
> +
>  enum intel_pdi_type {
>  	INTEL_PDI_IN = 0,
>  	INTEL_PDI_OUT = 1,
> @@ -922,7 +924,7 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
>  	struct sdw_master_prop *prop = &bus->prop;
>  	struct fwnode_handle *link;
>  	char name[32];
> -	int nval, i;
> +	u32 quirk_mask;
>  
>  	/* Find master handle */
>  	snprintf(name, sizeof(name),
> @@ -937,6 +939,14 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
>  	fwnode_property_read_u32(link,
>  				 "intel-sdw-ip-clock",
>  				 &prop->mclk_freq);
> +
> +	fwnode_property_read_u32(link,
> +				 "intel-quirk-mask",
> +				 &quirk_mask);
> +
> +	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
> +		prop->hw_disabled = true;
> +
>  	return 0;
>  }
>  
> @@ -997,6 +1007,12 @@ static int intel_probe(struct platform_device *pdev)
>  		goto err_master_reg;
>  	}
>  
> +	if (sdw->cdns.bus.prop.hw_disabled) {
> +		dev_info(&pdev->dev, "SoundWire master %d is disabled, ignoring\n",
> +			 sdw->cdns.bus.link_id);
> +		return 0;
> +	}
> +
>  	/* Initialize shim and controller */
>  	intel_link_power_up(sdw);
>  	intel_shim_init(sdw);
> @@ -1050,9 +1066,11 @@ static int intel_remove(struct platform_device *pdev)
>  
>  	sdw = platform_get_drvdata(pdev);
>  
> -	intel_debugfs_exit(sdw);
> -	free_irq(sdw->res->irq, sdw);
> -	snd_soc_unregister_component(sdw->cdns.dev);
> +	if (!sdw->cdns.bus.prop.hw_disabled) {
> +		intel_debugfs_exit(sdw);
> +		free_irq(sdw->res->irq, sdw);
> +		snd_soc_unregister_component(sdw->cdns.dev);
> +	}
>  	sdw_delete_bus_master(&sdw->cdns.bus);
>  
>  	return 0;
> diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
> index c7dfc824be80..f78b076a8782 100644
> --- a/include/linux/soundwire/sdw.h
> +++ b/include/linux/soundwire/sdw.h
> @@ -380,6 +380,7 @@ struct sdw_slave_prop {
>   * @err_threshold: Number of times that software may retry sending a single
>   * command
>   * @mclk_freq: clock reference passed to SoundWire Master, in Hz.
> + * @hw_disabled: if true, the Master is not functional, typically due to pin-mux
>   */
>  struct sdw_master_prop {
>  	u32 revision;
> @@ -395,6 +396,7 @@ struct sdw_master_prop {
>  	bool dynamic_frame;
>  	u32 err_threshold;
>  	u32 mclk_freq;
> +	bool hw_disabled;

Do we have such cases where some of SoundWire links are disabled and
some enabled?

>  };
>  
>  int sdw_master_read_prop(struct sdw_bus *bus);
> -- 
> 2.20.1
> 

--