linux-kernel - [PATCH v2] ALSA: hda: cs35l56: Stop creating ALSA controls for firmware coefficients

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Message-ID: <20240730162907.300046-1-simont@opensource.cirrus.com>
Date: Tue, 30 Jul 2024 16:29:07 +0000
From: Simon Trimmer <simont@...nsource.cirrus.com>
To: <tiwai@...e.com>
CC: <linux-sound@...r.kernel.org>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>, <patches@...nsource.cirrus.com>,
        "Simon
 Trimmer" <simont@...nsource.cirrus.com>
Subject: [PATCH v2] 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.

As the ALSA controls for the firmware coefficients are not used in
normal operation they can all be hidden, but add a kernel parameter so
that they can be re-enabled for debugging.

Signed-off-by: Simon Trimmer <simont@...nsource.cirrus.com>
---
Changes in v2:
- v1 was accidentally the backport version for older kernels instead of
  the one for v6.11

 sound/pci/hda/cs35l56_hda.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/pci/hda/cs35l56_hda.c b/sound/pci/hda/cs35l56_hda.c
index 96d3f13c5abf..f2f623f713d1 100644
--- a/sound/pci/hda/cs35l56_hda.c
+++ b/sound/pci/hda/cs35l56_hda.c
@@ -23,6 +23,10 @@
 #include "hda_cs_dsp_ctl.h"
 #include "hda_generic.h"
 
+static bool expose_dsp_controls;
+module_param(expose_dsp_controls, bool, 0444);
+MODULE_PARM_DESC(expose_dsp_controls, "Expose firmware controls as ALSA controls 0=no (default), 1=yes");
+
  /*
   * The cs35l56_hda_dai_config[] reg sequence configures the device as
   *  ASP1_BCLK_FREQ = 3.072 MHz
@@ -613,7 +617,7 @@ static void cs35l56_hda_fw_load(struct cs35l56_hda *cs35l56)
 	 */
 	if (cs35l56->base.fw_patched)
 		cs_dsp_power_down(&cs35l56->cs_dsp);
-	else
+	else if (expose_dsp_controls)
 		add_dsp_controls_required = true;
 
 	cs35l56->base.fw_patched = false;
-- 
2.43.0