linux-kernel - [PATCH] ASoC: codecs: Fix WCD_MBHC_HPH_PA

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Message-Id: <988948f7f266aa00698704687537335b7e6a67b2.1634455711.git.christophe.jaillet@wanadoo.fr>
Date:   Sun, 17 Oct 2021 09:31:12 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     lgirdwood@...il.com, broonie@...nel.org, perex@...ex.cz,
        tiwai@...e.com, srinivas.kandagatla@...aro.org,
        yang.lee@...ux.alibaba.com
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] ASoC: codecs: Fix WCD_MBHC_HPH_PA_EN usage

'hphpa_on' is known to be false, so the if block at the end of the function
is dead code.

Turn it into a meaningful code by having 'hphpa_on' be static. Use is as a
flip-flop variable.

Fixes: 0e5c9e7ff899 ("ASoC: codecs: wcd: add multi button Headset detection support")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
The purpose of this patch is not to be correct (!) but to draw attention
on several points:
   - in 'wcd_mbhc_adc_hs_rem_irq()', the "if (hphpa_on)" path is dead code
     because 'hphpa_on' is known to be false
   - What is this magic number '3'?
     All 'wcd_mbhc_read_field()' look for 0 or non-0
   - a 'mutex_[un]lock()' in an IRQ handler looks spurious to me

Instead of this (likely broken) patch, it is likely that something is
missing elsewhere. Maybe in 'wcd_mbhc_adc_hs_ins_irq()'.
I also guess that 'hphpa_on' should be read for somewhere else.
---
 sound/soc/codecs/wcd-mbhc-v2.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wcd-mbhc-v2.c b/sound/soc/codecs/wcd-mbhc-v2.c
index 405128ccb4b0..783d8c35bc1b 100644
--- a/sound/soc/codecs/wcd-mbhc-v2.c
+++ b/sound/soc/codecs/wcd-mbhc-v2.c
@@ -1176,7 +1176,7 @@ static irqreturn_t wcd_mbhc_adc_hs_rem_irq(int irq, void *data)
 	struct wcd_mbhc *mbhc = data;
 	unsigned long timeout;
 	int adc_threshold, output_mv, retry = 0;
-	bool hphpa_on = false;
+	static bool hphpa_on = false;
 
 	mutex_lock(&mbhc->lock);
 	timeout = jiffies + msecs_to_jiffies(WCD_FAKE_REMOVAL_MIN_PERIOD_MS);
@@ -1212,6 +1212,9 @@ static irqreturn_t wcd_mbhc_adc_hs_rem_irq(int irq, void *data)
 
 	if (hphpa_on) {
 		hphpa_on = false;
+		wcd_mbhc_write_field(mbhc, WCD_MBHC_HPH_PA_EN, 0);
+	} else {
+		hphpa_on = true;
 		wcd_mbhc_write_field(mbhc, WCD_MBHC_HPH_PA_EN, 3);
 	}
 exit:
-- 
2.30.2