ALSA: hda: cs35l56: Stop creating ALSA controls for firmware coefficients

A number of laptops have gone to market with old firmware versions that
export controls that have since been hidden, but we can't just install a
newer firmware because the firmware for each product is customized and
qualified by the OEM. The issue is that alsactl save and restore has no
idea what controls are good to persist which can lead to
misconfiguration.

There is no reason that the UCM or user should need to interact with any
of the ALSA controls for the firmware coefficients so they can be
removed entirely, this also simplifies the driver.
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://patch.msgid.link/20240801143139.34549-1-simont@opensource.cirrus.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/cs35l56_hda.c

@@ -559,18 +559,6 @@ static void cs35l56_hda_release_firmware_files(const struct firmware *wmfw_firmw
 	kfree(coeff_filename);
 }
 
-static void cs35l56_hda_create_dsp_controls_work(struct work_struct *work)
-{
-	struct cs35l56_hda *cs35l56 = container_of(work, struct cs35l56_hda, control_work);
-	struct hda_cs_dsp_ctl_info info;
-
-	info.device_name = cs35l56->amp_name;
-	info.fw_type = HDA_CS_DSP_FW_MISC;
-	info.card = cs35l56->codec->card;
-
-	hda_cs_dsp_add_controls(&cs35l56->cs_dsp, &info);
-}
-
 static void cs35l56_hda_apply_calibration(struct cs35l56_hda *cs35l56)
 {
 	int ret;
@@ -595,26 +583,15 @@ static void cs35l56_hda_fw_load(struct cs35l56_hda *cs35l56)
 	char *wmfw_filename = NULL;
 	unsigned int preloaded_fw_ver;
 	bool firmware_missing;
-	bool add_dsp_controls_required = false;
 	int ret;
 
-	/*
-	 * control_work must be flushed before proceeding, but we can't do that
-	 * here as it would create a deadlock on controls_rwsem so it must be
-	 * performed before queuing dsp_work.
-	 */
-	WARN_ON_ONCE(work_busy(&cs35l56->control_work));
-
 	/*
 	 * Prepare for a new DSP power-up. If the DSP has had firmware
 	 * downloaded previously then it needs to be powered down so that it
-	 * can be updated and if hadn't been patched before then the controls
-	 * will need to be added once firmware download succeeds.
+	 * can be updated.
 	 */
 	if (cs35l56->base.fw_patched)
 		cs_dsp_power_down(&cs35l56->cs_dsp);
-	else
-		add_dsp_controls_required = true;
 
 	cs35l56->base.fw_patched = false;
 
@@ -698,15 +675,6 @@ static void cs35l56_hda_fw_load(struct cs35l56_hda *cs35l56)
 			  CS35L56_FIRMWARE_MISSING);
 	cs35l56->base.fw_patched = true;
 
-	/*
-	 * Adding controls is deferred to prevent a lock inversion - ALSA takes
-	 * the controls_rwsem when adding a control, the get() / put()
-	 * functions of a control are called holding controls_rwsem and those
-	 * that depend on running firmware wait for dsp_work() to complete.
-	 */
-	if (add_dsp_controls_required)
-		queue_work(system_long_wq, &cs35l56->control_work);
-
 	ret = cs_dsp_run(&cs35l56->cs_dsp);
 	if (ret)
 		dev_dbg(cs35l56->base.dev, "%s: cs_dsp_run ret %d\n", __func__, ret);
@@ -753,7 +721,6 @@ static int cs35l56_hda_bind(struct device *dev, struct device *master, void *mas
 	strscpy(comp->name, dev_name(dev), sizeof(comp->name));
 	comp->playback_hook = cs35l56_hda_playback_hook;
 
-	flush_work(&cs35l56->control_work);
 	queue_work(system_long_wq, &cs35l56->dsp_work);
 
 	cs35l56_hda_create_controls(cs35l56);
@@ -775,7 +742,6 @@ static void cs35l56_hda_unbind(struct device *dev, struct device *master, void *
 	struct hda_component *comp;
 
 	cancel_work_sync(&cs35l56->dsp_work);
-	cancel_work_sync(&cs35l56->control_work);
 
 	cs35l56_hda_remove_controls(cs35l56);
 
@@ -806,7 +772,6 @@ static int cs35l56_hda_system_suspend(struct device *dev)
 	struct cs35l56_hda *cs35l56 = dev_get_drvdata(dev);
 
 	cs35l56_hda_wait_dsp_ready(cs35l56);
-	flush_work(&cs35l56->control_work);
 
 	if (cs35l56->playing)
 		cs35l56_hda_pause(cs35l56);
@@ -1026,7 +991,6 @@ int cs35l56_hda_common_probe(struct cs35l56_hda *cs35l56, int hid, int id)
 	dev_set_drvdata(cs35l56->base.dev, cs35l56);
 
 	INIT_WORK(&cs35l56->dsp_work, cs35l56_hda_dsp_work);
-	INIT_WORK(&cs35l56->control_work, cs35l56_hda_create_dsp_controls_work);
 
 	ret = cs35l56_hda_read_acpi(cs35l56, hid, id);
 	if (ret)

sound/pci/hda/cs35l56_hda.h

@@ -23,7 +23,6 @@ struct cs35l56_hda {
 	struct cs35l56_base base;
 	struct hda_codec *codec;
 	struct work_struct dsp_work;
-	struct work_struct control_work;
 
 	int index;
 	const char *system_name;