linux-kernel - [PATCH v1 2/8] ALSA: hda: cs35l41: Assert reset before system suspend

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Date:   Thu, 26 Oct 2023 16:05:52 +0100
From:   Stefan Binding <sbinding@...nsource.cirrus.com>
To:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        "Mark Brown" <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <linux-sound@...r.kernel.org>, <patches@...nsource.cirrus.com>,
        "Stefan Binding" <sbinding@...nsource.cirrus.com>
Subject: [PATCH v1 2/8] ALSA: hda: cs35l41: Assert reset before system suspend

Some system suspend modes may remove power supplies.
To ensure we are not running during this time, we should assert reset.

Note: since the amps use a shared reset, asserting reset prior to
system suspend only works if the amps are suspended in the reverse
order to probe.

Signed-off-by: Stefan Binding <sbinding@...nsource.cirrus.com>
---
 sound/pci/hda/cs35l41_hda.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sound/pci/hda/cs35l41_hda.c b/sound/pci/hda/cs35l41_hda.c
index 28cb10ddd191..919e38213975 100644
--- a/sound/pci/hda/cs35l41_hda.c
+++ b/sound/pci/hda/cs35l41_hda.c
@@ -813,14 +813,17 @@ static int cs35l41_system_suspend(struct device *dev)
 
 	/* Shutdown DSP before system suspend */
 	ret = cs35l41_ready_for_reset(cs35l41);
-
 	if (ret)
 		dev_err(dev, "System Suspend Failed, not ready for Reset: %d\n", ret);
 
-	/*
-	 * Reset GPIO may be shared, so cannot reset here.
-	 * However beyond this point, amps may be powered down.
-	 */
+	if (cs35l41->reset_gpio) {
+		dev_info(cs35l41->dev, "Asserting Reset\n");
+		gpiod_set_value_cansleep(cs35l41->reset_gpio, 0);
+		usleep_range(2000, 2100);
+	}
+
+	dev_dbg(cs35l41->dev, "System Suspended\n");
+
 	return ret;
 }
 
-- 
2.34.1