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

From
Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Date
2026-09-07 11:32:22
Also in
linux-arm-msm, linux-sound, lkml
Reply to
Srinivas Kandagatla, 2026-09-07
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.
quoted hunk ↗ jump to hunk
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 <redacted>
---
 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.
quoted hunk ↗ jump to hunk
 	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);
 }
 
 /**
  
Thread (50 messages) 50 messages, 8 authors, last reply 2026-09-09
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