[RFC, PATCH] horizontal mouse wheel in mousedrv

[RFC, PATCH] horizontal mouse wheel in mousedrv

[Pierre Ossman]

From: Pierre Ossman <drzeus@drzeus.cx>

Support the horizontal wheel present on many mice via the
/dev/input/mice device by using the somewhat odd protocol extension
of sending double wheel movements for the extra wheel.

This is of course a rather error prone protocol extension, but it is
found in some hardware and works well enough in practice. It is also
the only horizontal wheel protocol supported by Xorg's mouse driver.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 78c3ea7..2976b42 100644
--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c
@@ -50,7 +50,7 @@ module_param(tap_time, uint, 0644);
 MODULE_PARM_DESC(tap_time, "Tap time for touchpads in absolute mode (msecs)");
 
 struct mousedev_hw_data {
-	int dx, dy, dz;
+	int dx, dy, dz, dw;
 	int x, y;
 	int abs_event;
 	unsigned long buttons;
@@ -85,7 +85,7 @@ enum mousedev_emul {
 };
 
 struct mousedev_motion {
-	int dx, dy, dz;
+	int dx, dy, dz, dw;
 	unsigned long buttons;
 };
 
@@ -215,6 +215,10 @@ static void mousedev_rel_event(struct mousedev *mousedev,
 	case REL_WHEEL:
 		mousedev->packet.dz -= value;
 		break;
+
+	case REL_HWHEEL:
+		mousedev->packet.dw += value;
+		break;
 	}
 }
 
@@ -297,9 +301,10 @@ static void mousedev_notify_readers(struct mousedev *mousedev,
 		p->dx += packet->dx;
 		p->dy += packet->dy;
 		p->dz += packet->dz;
+		p->dw += packet->dw;
 		p->buttons = mousedev->packet.buttons;
 
-		if (p->dx || p->dy || p->dz ||
+		if (p->dx || p->dy || p->dz || p->dw ||
 		    p->buttons != client->last_buttons)
 			client->ready = 1;
 
@@ -394,7 +399,7 @@ static void mousedev_event(struct input_handle *handle,
 			mousedev_notify_readers(mousedev_mix, &mousedev->packet);
 
 			mousedev->packet.dx = mousedev->packet.dy =
-				mousedev->packet.dz = 0;
+				mousedev->packet.dz = mousedev->packet.dw = 0;
 			mousedev->packet.abs_event = 0;
 		}
 		break;
@@ -602,8 +607,13 @@ static void mousedev_packet(struct mousedev_client *client,
 
 	switch (client->mode) {
 	case MOUSEDEV_EMUL_EXPS:
-		ps2_data[3] = mousedev_limit_delta(p->dz, 7);
-		p->dz -= ps2_data[3];
+		if (p->dw) {
+			ps2_data[3] = mousedev_limit_delta(2 * p->dw, 7);
+			p->dw -= ps2_data[3] / 2;
+		} else {
+			ps2_data[3] = mousedev_limit_delta(p->dz, 7);
+			p->dz -= ps2_data[3];
+		}
 		ps2_data[3] = (ps2_data[3] & 0x0f) | ((p->buttons & 0x18) << 1);
 		client->bufsiz = 4;
 		break;
@@ -625,7 +635,7 @@ static void mousedev_packet(struct mousedev_client *client,
 		break;
 	}
 
-	if (!p->dx && !p->dy && !p->dz) {
+	if (!p->dx && !p->dy && !p->dz && !p->dw) {
 		if (client->tail == client->head) {
 			client->ready = 0;
 			client->last_buttons = p->buttons;

Re: [RFC, PATCH] horizontal mouse wheel in mousedrv

[Dmitry Torokhov]

Hi Pierre,

On Dec 25, 2007 10:49 AM, Pierre Ossman <drzeus-list@drzeus.cx> wrote:
> From: Pierre Ossman <drzeus@drzeus.cx>
>
> Support the horizontal wheel present on many mice via the
> /dev/input/mice device by using the somewhat odd protocol extension
> of sending double wheel movements for the extra wheel.
>
> This is of course a rather error prone protocol extension, but it is
> found in some hardware and works well enough in practice. It is also
> the only horizontal wheel protocol supported by Xorg's mouse driver.
>

I'd rather not change the legacy mousedev driver. The extension is
rather non-standard and there is no telling what applications might
break. Please use evdev driver, it should support horizontal scrolling
AFAIK.

-- 
Dmitry

Re: [RFC, PATCH] horizontal mouse wheel in mousedrv

[Pierre Ossman]

On Thu, 3 Jan 2008 11:25:21 -0500
"Dmitry Torokhov" <dmitry.torokhov@gmail.com> wrote:

> 
> I'd rather not change the legacy mousedev driver. The extension is
> rather non-standard and there is no telling what applications might
> break. Please use evdev driver, it should support horizontal scrolling
> AFAIK.
> 

It does, but it doesn't support hot-plug. Not something the kernel can be blamed for, but for my use case it was easier to do this modification to the kernel rather than to teach Xorg hot-plug.

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

Re: [RFC, PATCH] horizontal mouse wheel in mousedrv

[Dmitry Torokhov]

On Jan 3, 2008 12:27 PM, Pierre Ossman <drzeus-list@drzeus.cx> wrote:
> On Thu, 3 Jan 2008 11:25:21 -0500
> "Dmitry Torokhov" <dmitry.torokhov@gmail.com> wrote:
>
> >
> > I'd rather not change the legacy mousedev driver. The extension is
> > rather non-standard and there is no telling what applications might
> > break. Please use evdev driver, it should support horizontal scrolling
> > AFAIK.
> >
>
> It does, but it doesn't support hot-plug. Not something the kernel can be blamed for, but for my use case it was easier to do this modification to the kernel rather than to teach Xorg hot-plug.
>

As far as I remember the hotplug for X is being actively developed at
the moment.

-- 
Dmitry