linux-kernel - Re: [PATCH v2] HID: apple: Workaround for non-Apple keyboards

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Date:   Tue, 31 May 2022 22:33:30 +0800
From:   Hilton Chain <hako@...rarare.space>
To:     José Expósito <jose.exposito89@...il.com>
Cc:     bryancain3@...il.com, jikos@...nel.org,
        benjamin.tissoires@...hat.com, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org
Subject: Re: [PATCH v2] HID: apple: Workaround for non-Apple keyboards

There's a bunch of non-Apple keyboard misuses Apple's vendor and product
id, causing hid_apple to be served for them. However they can't handle the
default fnmode.

This commit adds an array of non-Apple keyboards' device names, together
with a function apple_is_non_apple_keyboard() to identify and create
exception for them.

Signed-off-by: Hilton Chain <hako@...rarare.space>
---
 drivers/hid/hid-apple.c | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
index 42a568902f49..4429b25ae3d8 100644
--- a/drivers/hid/hid-apple.c
+++ b/drivers/hid/hid-apple.c
@@ -36,7 +36,7 @@
 #define APPLE_NUMLOCK_EMULATION	BIT(8)
 #define APPLE_RDESC_BATTERY	BIT(9)
 #define APPLE_BACKLIGHT_CTL	BIT(10)
-#define APPLE_IS_KEYCHRON	BIT(11)
+#define APPLE_IS_NON_APPLE	BIT(11)
 
 #define APPLE_FLAG_FKEY		0x01
 
@@ -65,6 +65,10 @@ MODULE_PARM_DESC(swap_fn_leftctrl, "Swap the Fn and left Control keys. "
 		"(For people who want to keep PC keyboard muscle memory. "
 		"[0] = as-is, Mac layout, 1 = swapped, PC layout)");
 
+struct apple_non_apple_keyboard {
+	char *name;
+};
+
 struct apple_sc_backlight {
 	struct led_classdev cdev;
 	struct hid_device *hdev;
@@ -313,6 +317,29 @@ static const struct apple_key_translation swapped_fn_leftctrl_keys[] = {
 	{ }
 };
 
+static const struct apple_non_apple_keyboard non_apple_keyboards[] = {
+	{ "SONiX USB DEVICE" },
+	{ "Keychron" },
+	{ }
+};
+
+static bool apple_is_non_apple_keyboard(struct hid_device *hdev)
+{
+	unsigned long i;
+	unsigned long non_apple_total = sizeof(non_apple_keyboards) /
+					sizeof(struct apple_non_apple_keyboard);
+
+	for (i = 0; i < non_apple_total; i++) {
+		char *non_apple = non_apple_keyboards[i].name;
+
+		if (non_apple && strlen(non_apple) &&
+				strncmp(hdev->name, non_apple, strlen(non_apple)) == 0)
+			return true;
+	}
+
+	return false;
+}
+
 static inline void apple_setup_key_translation(struct input_dev *input,
 		const struct apple_key_translation *table)
 {
@@ -363,7 +390,7 @@ static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
 	}
 
 	if (fnmode == 3) {
-		real_fnmode = (asc->quirks & APPLE_IS_KEYCHRON) ? 2 : 1;
+		real_fnmode = (asc->quirks & APPLE_IS_NON_APPLE) ? 2 : 1;
 	} else {
 		real_fnmode = fnmode;
 	}
@@ -667,11 +694,12 @@ static int apple_input_configured(struct hid_device *hdev,
 	if ((asc->quirks & APPLE_HAS_FN) && !asc->fn_found) {
 		hid_info(hdev, "Fn key not found (Apple Wireless Keyboard clone?), disabling Fn key handling\n");
 		asc->quirks &= ~APPLE_HAS_FN;
-	}
 
-	if (strncmp(hdev->name, "Keychron", 8) == 0) {
-		hid_info(hdev, "Keychron keyboard detected; function keys will default to fnmode=2 behavior\n");
-		asc->quirks |= APPLE_IS_KEYCHRON;
+		if (apple_is_non_apple_keyboard(hdev)) {
+			hid_info(hdev,
+				"Non-apple keyboard detected; function keys will default to fnmode=2 behavior\n");
+			asc->quirks |= APPLE_IS_NON_APPLE;
+		}
 	}
 
 	return 0;

base-commit: 8ab2afa23bd197df47819a87f0265c0ac95c5b6a
-- 
2.36.1