linux-kernel - [PATCH v2 2/2] Input: cros-ec-keyb - skip keyboard registration for switches compatible

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Date:   Fri, 29 Apr 2022 16:31:12 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
        chrome-platform@...ts.linux.dev,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        "Joseph S. Barrera III" <joebar@...omium.org>
Subject: [PATCH v2 2/2] Input: cros-ec-keyb - skip keyboard registration for switches compatible

In commit 4352e23a7ff2 ("Input: cros-ec-keyb - only register keyboard if
rows/columns exist") we skipped registration of the keyboard if the
row/columns property didn't exist, but that has a slight problem for
existing DTBs. The DTBs have the rows/columns properties, so removing
the properties to indicate only switches exist makes this keyboard
driver fail to probe, resulting in broken power and volume buttons. Ease
the migration of existing DTBs by skipping keyboard registration if the
google,cros-ec-keyb-switches compatible exists.

The end result is that new DTBs can either choose to remove the matrix
keymap properties or leave them in place and add this new compatible
indicating the matrix keyboard properties should be ignored. Existing
DTBs will continue to work, but they will keep registering the keyboard
that does nothing. To fix that problem we can add this extra compatible
to existing DTBs and the keyboard will stop being registered. Finally,
if google,cros-ec-keyb is missing then this driver won't even attempt to
register the matrix keyboard.

Cc: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: <devicetree@...r.kernel.org>
Cc: Benson Leung <bleung@...omium.org>
Cc: Guenter Roeck <groeck@...omium.org>
Cc: Douglas Anderson <dianders@...omium.org>
Cc: Hsin-Yi Wang <hsinyi@...omium.org>
Cc: "Joseph S. Barrera III" <joebar@...omium.org>
Fixes: 4352e23a7ff2 ("Input: cros-ec-keyb - only register keyboard if rows/columns exist")
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/input/keyboard/cros_ec_keyb.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index eef909e52e23..1bbe2987bf52 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -536,6 +536,12 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
 	u32 *physmap;
 	u32 key_pos;
 	unsigned int row, col, scancode, n_physmap;
+	bool register_keyboard;
+
+	/* Skip matrix registration if no keyboard */
+	register_keyboard = device_get_match_data(dev);
+	if (!register_keyboard)
+		return 0;

 	/*
 	 * No rows and columns? There isn't a matrix but maybe there are
@@ -718,8 +724,13 @@ static int cros_ec_keyb_remove(struct platform_device *pdev)

 #ifdef CONFIG_OF
 static const struct of_device_id cros_ec_keyb_of_match[] = {
-	{ .compatible = "google,cros-ec-keyb" },
-	{},
+	{
+		/* Must be first */
+		.compatible = "google,cros-ec-keyb",
+		.data = (void *)true
+	},
+	{ .compatible = "google,cros-ec-keyb-switches" },
+	{}
 };
 MODULE_DEVICE_TABLE(of, cros_ec_keyb_of_match);
 #endif
-- 
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