linux-kernel - [PATCH v7 1/3] HID: logitech-hidpp: Support translations from short to long reports

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Date:   Sun, 20 Oct 2019 04:41:15 +0000
From:   Mazin Rezk <mnrzk@...tonmail.com>
To:     "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>
Cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        "jikos@...nel.org" <jikos@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Filipe Laíns <lains@...hlinux.org>,
        "mnrzk@...tonmail.com" <mnrzk@...tonmail.com>
Subject: [PATCH v7 1/3] HID: logitech-hidpp: Support translations from short to long reports

This patch allows short reports to be translated into long reports.

hidpp_validate_device now returns a u8 instead of a bool which represents
the supported reports. The corresponding bits (i.e.
HIDPP_REPORT_*_SUPPORTED) are set if an HID++ report is supported.

If a short report is being sent and the device does not support it, it is
instead sent as a long report.

Thanks,
Mazin

Signed-off-by: Mazin Rezk <mnrzk@...tonmail.com>
---
 drivers/hid/hid-logitech-hidpp.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index e9bba282f9c1..ee604b17514f 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -49,6 +49,10 @@ MODULE_PARM_DESC(disable_tap_to_click,
 #define HIDPP_REPORT_LONG_LENGTH		20
 #define HIDPP_REPORT_VERY_LONG_MAX_LENGTH	64

+#define HIDPP_REPORT_SHORT_SUPPORTED		BIT(0)
+#define HIDPP_REPORT_LONG_SUPPORTED		BIT(1)
+#define HIDPP_REPORT_VERY_LONG_SUPPORTED	BIT(2)
+
 #define HIDPP_SUB_ID_CONSUMER_VENDOR_KEYS	0x03
 #define HIDPP_SUB_ID_ROLLER			0x05
 #define HIDPP_SUB_ID_MOUSE_EXTRA_BTNS		0x06
@@ -183,6 +187,7 @@ struct hidpp_device {

 	unsigned long quirks;
 	unsigned long capabilities;
+	u8 supported_reports;

 	struct hidpp_battery battery;
 	struct hidpp_scroll_counter vertical_wheel_counter;
@@ -340,6 +345,11 @@ static int hidpp_send_rap_command_sync(struct hidpp_device *hidpp_dev,
 	struct hidpp_report *message;
 	int ret, max_count;

+	/* Send as long report if short reports are not supported. */
+	if (report_id == REPORT_ID_HIDPP_SHORT &&
+	    !(hidpp_dev->supported_reports & HIDPP_REPORT_SHORT_SUPPORTED))
+		report_id = REPORT_ID_HIDPP_LONG;
+
 	switch (report_id) {
 	case REPORT_ID_HIDPP_SHORT:
 		max_count = HIDPP_REPORT_SHORT_LENGTH - 4;
@@ -3458,10 +3468,11 @@ static int hidpp_get_report_length(struct hid_device *hdev, int id)
 	return report->field[0]->report_count + 1;
 }

-static bool hidpp_validate_device(struct hid_device *hdev)
+static u8 hidpp_validate_device(struct hid_device *hdev)
 {
 	struct hidpp_device *hidpp = hid_get_drvdata(hdev);
-	int id, report_length, supported_reports = 0;
+	int id, report_length;
+	u8 supported_reports = 0;

 	id = REPORT_ID_HIDPP_SHORT;
 	report_length = hidpp_get_report_length(hdev, id);
@@ -3469,7 +3480,7 @@ static bool hidpp_validate_device(struct hid_device *hdev)
 		if (report_length < HIDPP_REPORT_SHORT_LENGTH)
 			goto bad_device;

-		supported_reports++;
+		supported_reports |= HIDPP_REPORT_SHORT_SUPPORTED;
 	}

 	id = REPORT_ID_HIDPP_LONG;
@@ -3478,7 +3489,7 @@ static bool hidpp_validate_device(struct hid_device *hdev)
 		if (report_length < HIDPP_REPORT_LONG_LENGTH)
 			goto bad_device;

-		supported_reports++;
+		supported_reports |= HIDPP_REPORT_LONG_SUPPORTED;
 	}

 	id = REPORT_ID_HIDPP_VERY_LONG;
@@ -3488,7 +3499,7 @@ static bool hidpp_validate_device(struct hid_device *hdev)
 		    report_length > HIDPP_REPORT_VERY_LONG_MAX_LENGTH)
 			goto bad_device;

-		supported_reports++;
+		supported_reports |= HIDPP_REPORT_VERY_LONG_SUPPORTED;
 		hidpp->very_long_report_length = report_length;
 	}

@@ -3536,7 +3547,9 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	/*
 	 * Make sure the device is HID++ capable, otherwise treat as generic HID
 	 */
-	if (!hidpp_validate_device(hdev)) {
+	hidpp->supported_reports = hidpp_validate_device(hdev);
+
+	if (!hidpp->supported_reports) {
 		hid_set_drvdata(hdev, NULL);
 		devm_kfree(&hdev->dev, hidpp);
 		return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
--
2.23.0