Re: [PATCH v2 04/11] ASoC: SDCA: add hw_ops with hw_init hook

[Pierre-Louis Bossart]

On 9/7/26 10:37, Srinivas Kandagatla wrote:
> Add struct sdca_class_hw_ops with a hw_init callback that runs from
> sdca_class_probe() before the class regmap is created.  Codec drivers
> use it to enable supplies, toggle reset GPIOs and program initial
> vendor register state.

It'd be good to clarify when this hw_init() is supposed to run. Probe
and hardware being available are usually two different things. I think
this relies on a behavior at the device level where the function
subdevices are only created after SoundWire device enumeration.

Also the 'hw_init' naming could be confusing, this is used in many codec
drivers to track if the hardware has previously been initialized.

> sdca_class_probe() gains an optional const struct sdca_class_hw_ops *
> argument (NULL for pure-generic SDCA parts) and stashes it on
> sdca_class_drv for later use.
> 
> No functional change for the built-in class_sdw_driver, which passes
> NULL.
> 
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxxxxxxxx>
> ---
>  include/sound/sdca_class.h  | 17 ++++++++++++++++-
>  sound/soc/sdca/sdca_class.c | 15 +++++++++++++--
>  2 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/include/sound/sdca_class.h b/include/sound/sdca_class.h
> index c6063f22be7a..3342937d09fd 100644
> --- a/include/sound/sdca_class.h
> +++ b/include/sound/sdca_class.h
> @@ -20,6 +20,17 @@ struct regmap;
>  struct sdw_slave;
>  struct sdca_function_data;
>  
> +/**
> + * struct sdca_class_hw_ops - optional codec hardware callbacks
> + * @hw_init: enable supplies, toggle reset, etc.  Runs from sdca_class_probe()
> + *           before the class regmap is created and before the slave is
> + *           ATTACHED; callers needing bus I/O must sdw_slave_wait_for_init()
> + *           first.
> + */
> +struct sdca_class_hw_ops {
> +	int (*hw_init)(struct sdw_slave *slave);
> +};
> +
>  struct sdca_class_drv {
>  	struct device *dev;
>  	struct regmap *dev_regmap;
> @@ -27,6 +38,8 @@ struct sdca_class_drv {
>  
>  	struct sdca_interrupt_info *irq_info;
>  
> +	const struct sdca_class_hw_ops *hw_ops;
> +
>  	struct mutex regmap_lock;
>  	/* Serialise function initialisations */
>  	struct mutex init_lock;
> @@ -35,7 +48,9 @@ struct sdca_class_drv {
>  
>  /* Library helpers used by codec-specific SDCA SoundWire drivers. */
>  int sdca_class_read_prop(struct sdw_slave *sdw);
> -int sdca_class_probe(struct sdw_slave *sdw, struct sdca_class_drv *drv);
> +int sdca_class_probe(struct sdw_slave *sdw,
> +		     struct sdca_class_drv *drv,
> +		     const struct sdca_class_hw_ops *hw_ops);
>  void sdca_class_remove(struct sdca_class_drv *drv);
>  
>  /*
> diff --git a/sound/soc/sdca/sdca_class.c b/sound/soc/sdca/sdca_class.c
> index b952fa6eb802..374de7d9e0b5 100644
> --- a/sound/soc/sdca/sdca_class.c
> +++ b/sound/soc/sdca/sdca_class.c
> @@ -153,6 +153,8 @@ static void class_boot_work(struct work_struct *work)
>   *       allocation and sets its own dev_set_drvdata() -- the framework
>   *       does not touch drvdata.  Typically embedded in the codec's own
>   *       priv struct so codec drivers can keep per-slave state.
> + * @hw_ops: optional device-specific hw_ops (may be NULL for pure-generic
> + *          SDCA parts that need no quirks)
>   *
>   * Codec-specific SoundWire drivers call this from their .probe after
>   * allocating a struct sdca_class_drv (usually embedded in their own
> @@ -160,7 +162,9 @@ static void class_boot_work(struct work_struct *work)
>   * sdca_class_drv fields, sets up the class regmap, and queues the
>   * deferred boot work.
>   */
> -int sdca_class_probe(struct sdw_slave *sdw, struct sdca_class_drv *drv)
> +int sdca_class_probe(struct sdw_slave *sdw,
> +		     struct sdca_class_drv *drv,
> +		     const struct sdca_class_hw_ops *hw_ops)
>  {
>  	struct device *dev = &sdw->dev;
>  	struct regmap_config *dev_config;
> @@ -178,9 +182,16 @@ int sdca_class_probe(struct sdw_slave *sdw, struct sdca_class_drv *drv)
>  
>  	drv->dev = dev;
>  	drv->sdw = sdw;
> +	drv->hw_ops = hw_ops;
>  	mutex_init(&drv->regmap_lock);
>  	mutex_init(&drv->init_lock);
>  
> +	if (hw_ops && hw_ops->hw_init) {
> +		ret = hw_ops->hw_init(sdw);
> +		if (ret)
> +			return dev_err_probe(dev, ret, "hw_init failed\n");
> +	}
> +

nit-pick: should the INIT_WORK be moved higher before this hw_init()? It
has nothing to do with regmap and we'd lose the requirement that
hw_init() be run before regmap inits.

>  	INIT_WORK(&drv->boot_work, class_boot_work);
>  
>  	dev_config->lock_arg = &drv->regmap_lock;
> @@ -222,7 +233,7 @@ static int class_sdw_probe(struct sdw_slave *sdw, const struct sdw_device_id *id
>  
>  	dev_set_drvdata(&sdw->dev, drv);
>  
> -	return sdca_class_probe(sdw, drv);
> +	return sdca_class_probe(sdw, drv, NULL);
>  }
>  
>  /**