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Fix for using mousewheel in fbcon mode #46

SDLBugzilla opened this issue Feb 10, 2021 · 0 comments

Fix for using mousewheel in fbcon mode #46

SDLBugzilla opened this issue Feb 10, 2021 · 0 comments


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@SDLBugzilla SDLBugzilla commented Feb 10, 2021

This bug report was migrated from our old Bugzilla tracker.

Reported in version: HG 1.2
Reported for operating system, platform: Linux, x86

Comments on the original bug report:

On 2006-01-21 15:13:28 +0000, Sam Lantinga wrote:

Date: Mon, 24 Feb 2003 13:35:11 +0800
From: "Leonidas"
Subject: [SDL] Re: Trigger mouse wheel event -- not in X-environment

I have looked into the codes for the IMPS/2 mouse wheel mode of fbcon driver.
But I found something weird.

Here's the original codes to set a mouse device into IMPS/2 mode in libSDL.
In the file src/video/fbcon/SDL_fbevents.c
In function static int set_imps2_mode(int fd)
Uint8 set_imps2[] = {0xf3, 200, 0xf3, 100, 0xf3, 80};
Uint8 reset = 0xff;
fd_set fdset;
struct timeval tv;
int retval = 0;

// Set mouse device fd into IMPS/2 mode
if ( write(fd, &set_imps2, sizeof(set_imps2)) == sizeof(set_imps2) ) {
// ??? then RESET it..???
if (write(fd, &reset, sizeof (reset)) == sizeof (reset) ) {
retval = 1;

Since it sets IMPS/2 mode then reset it, so you will never get a mouse into
IMPS/2 mode to use its wheel.
What I did to make the wheel usable is remove the RESET codes.
if ( write(fd, &set_imps2, sizeof(set_imps2)) == sizeof(set_imps2) ) {
if (write(fd, &reset, sizeof (reset)) == sizeof (reset) ) {
retval = 1;
And in FB_OpenMouse(_THIS)
Make the device /dev/psaux to be setted into imps2 mode such that it can be
detected its a imps/2 mouse or not.
(my mouse device is on ps2, but the codes only set /dev/input/mice device
Then I have done, I can use the mouse wheel when SDL uses frame buff driver.

I dont exactly know I did right or wrong, I just change it for my usuage.
Correct me please, if I did something wrong.

Best regards,
Li Tsung Lin
IAP Product Dept. Engineer
EeRise Corp. (Image Processing System, Computer Vision System)
Hsin Tien, Taipei Hsien, Taiwan, R.O.C.
WebSite: Http://

On 2006-01-27 11:23:19 +0000, Ryan C. Gordon wrote:

Setting Sam as "QA Contact" on all bugs (even resolved ones) so he'll definitely be in the loop to any further discussion here about SDL.


On 2006-03-22 02:23:06 +0000, Sam Lantinga wrote:

I fixed this in CVS, I think. Ryan, can you check my changes?

On 2006-03-22 03:36:05 +0000, Ryan C. Gordon wrote:

Works here with fbcon, but it worked before the patch with my hardware, too.

We'll call it good to go. :)


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