linux-kernel - [PATCH v2 7/8] ASoC: cs42l42: Don't set idle_bias

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230118160452.2385494-8-sbinding@opensource.cirrus.com>
Date:   Wed, 18 Jan 2023 16:04:51 +0000
From:   Stefan Binding <sbinding@...nsource.cirrus.com>
To:     Mark Brown <broonie@...nel.org>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>,
        Stefan Binding <sbinding@...nsource.cirrus.com>
Subject: [PATCH v2 7/8] ASoC: cs42l42: Don't set idle_bias_on

From: Richard Fitzgerald <rf@...nsource.cirrus.com>

idle_bias_on was set because cs42l42 has a "VMID" type pseudo-midrail
supply (named FILT+), and these typically take a long time to charge.
But the driver never enabled pm_runtime so it would never have powered-
down the cs42l42 anyway.

In fact, FILT+ can charge to operating voltage within 12.5 milliseconds
of enabling HP or ADC. This time is already covered by the startup
delay of the HP/ADC.

The datasheet warning about FILT+ taking up to 1 second to charge only
applies in the special cases that either the PLL is started or
DETECT_MODE set to non-zero while both HP and ADC are off. The driver
never does either of these.

Removing idle_bias_on allows the Soundwire host controller to suspend
if there isn't a snd_soc_jack handler registered.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
Signed-off-by: Stefan Binding <sbinding@...nsource.cirrus.com>
---
 sound/soc/codecs/cs42l42.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index a92499876ce2a..aa2223bfb885a 100644
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -597,7 +597,6 @@ const struct snd_soc_component_driver cs42l42_soc_component = {
 	.num_dapm_routes	= ARRAY_SIZE(cs42l42_audio_map),
 	.controls		= cs42l42_snd_controls,
 	.num_controls		= ARRAY_SIZE(cs42l42_snd_controls),
-	.idle_bias_on		= 1,
 	.endianness		= 1,
 };
 EXPORT_SYMBOL_NS_GPL(cs42l42_soc_component, SND_SOC_CS42L42_CORE);
-- 
2.34.1