linux-kernel - [PATCH 1/3] ASoC: dt-bindings: cs42l42: Correct description of ts-inv

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Message-ID: <20211116162652.45225-4-rf@opensource.cirrus.com>
Date:   Tue, 16 Nov 2021 16:26:47 +0000
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 1/3] ASoC: dt-bindings: cs42l42: Correct description of ts-inv

This swaps the descriptions of the 0 and 1 values to match
what the driver actually does with this property.

The background here is somewhat confusing. The codec has two
invert bits for the tip sense. The DT property should have been
for the TIP_SENSE_INV bit, which is the one that controls the
detect block. Due to some misunderstanding of the hardware the
driver actually implemented setting of the TS_INV bit, which is
only for swapping the sense of the interrupt bits. The description
was taken from the datasheet and refers to TIP_SENSE_INV but
unfortunately TS_INV has a different purpose and the net effect
of changing it is the reverse of what was intended (this is not
clearly described in the datasheet). So the ts-inv settings have
always done the exact opposite of what the description said.

Given the age of the driver, it's too late now to swap the meanings
of the values, so the description is changed to match the behaviour.
They have been annotated with the terminology used in the datasheet
to avoid the confusion of which one corresponds to what the datasheet
calls "inverted tip sense".

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
Fixes: da16c5579353 ("ASoC: cs42l42: Add devicetree bindings for CS42L42")
---
 Documentation/devicetree/bindings/sound/cs42l42.txt | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/cs42l42.txt b/Documentation/devicetree/bindings/sound/cs42l42.txt
index 5d416fdaf023..3b7705623980 100644
--- a/Documentation/devicetree/bindings/sound/cs42l42.txt
+++ b/Documentation/devicetree/bindings/sound/cs42l42.txt
@@ -19,13 +19,14 @@ Optional properties:
   (See Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
   for further information relating to interrupt properties)

-  - cirrus,ts-inv : Boolean property. For jacks that invert the tip sense
-  polarity. Normal jacks will short tip sense pin to HS1 when headphones are
-  plugged in and leave tip sense floating when not plugged in. Inverting jacks
-  short tip sense when unplugged and float when plugged in.
+  - cirrus,ts-inv : Boolean property. Sets the behaviour of the jack plug
+  detect switch.

-  0 = (Default) Non-inverted
-  1 = Inverted
+  0 = (Default) Shorted to tip when unplugged, open when plugged.
+      This is "inverted tip sense (ITS)" in the datasheet.
+
+  1 = Open when unplugged, shorted to tip when plugged.
+      This is "normal tip sense (TS)" in the datasheet.

   - cirrus,ts-dbnc-rise : Debounce the rising edge of TIP_SENSE_PLUG. With no
   debounce, the tip sense pin might be noisy on a plug event.
-- 
2.11.0