[PATCH] HID: update PenMount USB report descriptor so that only one button is reported

Subsystems: hid core layer, the rest

STALE4002d

3 messages, 2 authors, 2015-10-13 · open the first message on its own page

[PATCH] HID: update PenMount USB report descriptor so that only one button is reported

From: Andrew Shadura <hidden>
Date: 2015-07-20 12:08:17

PenMount USB resistive touchscreen reports it has three buttons, while in reality
it doesn't have any and doesn't support active styli, and only generates touch
events.

Signed-off-by: Andrew Shadura <redacted>
---
 drivers/hid/hid-penmount.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/hid/hid-penmount.c b/drivers/hid/hid-penmount.c
index c11dce8..4e12502 100644
--- a/drivers/hid/hid-penmount.c
+++ b/drivers/hid/hid-penmount.c

@@ -30,6 +30,21 @@ static int penmount_input_mapping(struct hid_device *hdev,
 	return 0;
 }
 
+static __u8 *penmount_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+        unsigned int *rsize)
+{
+	if (*rsize == 76 &&
+		rdesc[2] == 0x09 && rdesc[3] == 0x02 /* mouse */ &&
+		rdesc[22] == 0x05 && rdesc[23] == 0x09 /* button */ &&
+		rdesc[26] == 0x29 && rdesc[27] == 0x03 /* maximum */) {
+		hid_info(hdev,
+			"fixing up PenMount USB touchscreen report descriptor\n");
+
+		rdesc[27] = 0x01; /* just one button */
+	}
+	return rdesc;
+}
+
 static const struct hid_device_id penmount_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_PENMOUNT, USB_DEVICE_ID_PENMOUNT_6000) },
 	{ }

@@ -39,6 +54,7 @@ MODULE_DEVICE_TABLE(hid, penmount_devices);
 static struct hid_driver penmount_driver = {
 	.name = "hid-penmount",
 	.id_table = penmount_devices,
+	.report_fixup = penmount_report_fixup,
 	.input_mapping = penmount_input_mapping,
 };

-- 
2.1.4

[PATCH v2] HID: update PenMount USB report descriptor so that only one button is reported

From: Andrew Shadura <hidden>
Date: 2015-07-23 16:20:28

PenMount USB resistive touchscreen reports it has three buttons, while in reality
it doesn't have any and doesn't support active styli, and only generates touch
events.

Signed-off-by: Andrew Shadura <redacted>
---
 drivers/hid/hid-penmount.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/hid/hid-penmount.c b/drivers/hid/hid-penmount.c
index c11dce8..98ea1c12 100644
--- a/drivers/hid/hid-penmount.c
+++ b/drivers/hid/hid-penmount.c

@@ -30,6 +30,23 @@ static int penmount_input_mapping(struct hid_device *hdev,
 	return 0;
 }
 
+static __u8 *penmount_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+        unsigned int *rsize)
+{
+	if (*rsize == 76 &&
+		rdesc[2] == 0x09 && rdesc[3] == 0x02 /* mouse */ &&
+		rdesc[22] == 0x05 && rdesc[23] == 0x09 /* button */ &&
+		rdesc[26] == 0x29 && rdesc[27] == 0x03 /* maximum */ &&
+		rdesc[32] == 0x95 && rdesc[33] == 0x02 /* report count */) {
+		hid_info(hdev,
+			"fixing up PenMount USB touchscreen report descriptor\n");
+
+		rdesc[27] = 0x01; /* just one button */
+		rdesc[33] = 0x01; /* just one report */
+	}
+	return rdesc;
+}
+
 static const struct hid_device_id penmount_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_PENMOUNT, USB_DEVICE_ID_PENMOUNT_6000) },
 	{ }

@@ -39,6 +56,7 @@ MODULE_DEVICE_TABLE(hid, penmount_devices);
 static struct hid_driver penmount_driver = {
 	.name = "hid-penmount",
 	.id_table = penmount_devices,
+	.report_fixup = penmount_report_fixup,
 	.input_mapping = penmount_input_mapping,
 };

-- 
2.1.4

Re: [PATCH v2] HID: update PenMount USB report descriptor so that only one button is reported

From: Benjamin Tissoires <hidden>
Date: 2015-10-13 14:08:02

Hi Andrew,

[resurrecting this following a ping from Andrew]

On Thu, Jul 23, 2015 at 12:20 PM, Andrew Shadura
[off-list ref] wrote:

quoted hunk

PenMount USB resistive touchscreen reports it has three buttons, while in reality
it doesn't have any and doesn't support active styli, and only generates touch
events.

Signed-off-by: Andrew Shadura <redacted>
---
 drivers/hid/hid-penmount.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/hid/hid-penmount.c b/drivers/hid/hid-penmount.c
index c11dce8..98ea1c12 100644
--- a/drivers/hid/hid-penmount.c
+++ b/drivers/hid/hid-penmount.c

@@ -30,6 +30,23 @@ static int penmount_input_mapping(struct hid_device *hdev,
        return 0;
 }

+static __u8 *penmount_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+        unsigned int *rsize)
+{
+       if (*rsize == 76 &&
+               rdesc[2] == 0x09 && rdesc[3] == 0x02 /* mouse */ &&
+               rdesc[22] == 0x05 && rdesc[23] == 0x09 /* button */ &&
+               rdesc[26] == 0x29 && rdesc[27] == 0x03 /* maximum */ &&
+               rdesc[32] == 0x95 && rdesc[33] == 0x02 /* report count */) {
+               hid_info(hdev,
+                       "fixing up PenMount USB touchscreen report descriptor\n");
+
+               rdesc[27] = 0x01; /* just one button */
+               rdesc[33] = 0x01; /* just one report */

This is wrong. Changing this value shifts all the parsing of the rest
of the report descriptor. So if this is the last field in the current
report, then it might work. If not, then you are screwing the rest of
the report.

You can have 2 solutions to fix that:
- either you still use a report fixup and you add an extra const field
with a vendor usage page after this one (but that means allocating a
new report descriptor slightly larger)
- either you don't use a report fixup at all and ignore the extra
buttons in .input_mapping().

Cheers,
Benjamin

quoted hunk

+       }
+       return rdesc;
+}
+
 static const struct hid_device_id penmount_devices[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_PENMOUNT, USB_DEVICE_ID_PENMOUNT_6000) },
        { }

@@ -39,6 +56,7 @@ MODULE_DEVICE_TABLE(hid, penmount_devices);
 static struct hid_driver penmount_driver = {
        .name = "hid-penmount",
        .id_table = penmount_devices,
+       .report_fixup = penmount_report_fixup,
        .input_mapping = penmount_input_mapping,
 };

--

2.1.4

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