| | 1 | The double-pressing plaguing the Motorola Milestone 2 is a software-bug, as |
| | 2 | Motorola forgot to enable the generic android gpio debounce code in their |
| | 3 | keyboard-driver. |
| | 4 | |
| | 5 | When looking at the Motorola Milestone 2 kernel, which is available at |
| | 6 | https://opensource.motorola.com/sf/projects/milestone (Milestone-2 2.2.16, |
| | 7 | kernel.tar.gz), the following code can be found in the file |
| | 8 | arch/arm/mach-omap2/board-sholes-keypad.c: |
| | 9 | [CODE] |
| | 10 | static struct gpio_event_matrix_info sholes_keypad_matrix_info = { |
| | 11 | .info.func = gpio_event_matrix_func, |
| | 12 | .keymap = sholes_p3_keymap, |
| | 13 | .output_gpios = sholes_col_gpios, |
| | 14 | .input_gpios = sholes_row_gpios, |
| | 15 | .noutputs = ARRAY_SIZE(sholes_col_gpios), |
| | 16 | .ninputs = ARRAY_SIZE(sholes_row_gpios), |
| | 17 | .settle_time.tv.nsec = 40 * NSEC_PER_USEC, |
| | 18 | .poll_time.tv.nsec = 20 * NSEC_PER_MSEC, |
| | 19 | .flags = GPIOKPF_LEVEL_TRIGGERED_IRQ | GPIOKPF_REMOVE_PHANTOM_KEYS | |
| | 20 | GPIOKPF_PRINT_UNMAPPED_KEYS /*| GPIOKPF_PRINT_MAPPED_KEYS*/ |
| | 21 | }; |
| | 22 | [/CODE] |
| | 23 | |
| | 24 | But the header defining this struct (include/linux/gpio_event.h) adds another |
| | 25 | very interesting member: |
| | 26 | [CODE] |
| | 27 | struct gpio_event_matrix_info { |
| | 28 | ... |
| | 29 | ktime_t debounce_delay; |
| | 30 | ... |
| | 31 | }; |
| | 32 | [/CODE] |
| | 33 | |
| | 34 | This debounce_delay is 0 as it is never initialized, and so the debouncing code |
| | 35 | in drivers/input/misc/gpio_matrix.c does nothing. The easy fix for this problem |
| | 36 | would be to recompile the kernel and set this member to the value used in other |
| | 37 | android handsets (5ms). But "thanks" to the locked bootloader this is |
| | 38 | impossible. |
| | 39 | |
| | 40 | So the only solution to this is an ugly hack, which searches for the structure |
| | 41 | in memory and sets debounce_delay to an useful value. I have written a |
| | 42 | kernel-module which does just that. It's code can be found at: |
| | 43 | http://git.zerfleddert.de/cgi-bin/gitweb.cgi/ms2-fixes |
| | 44 | (And this is its README file) |
| | 45 | |
| | 46 | As I assume not everybody wants to go through the pain of setting up a |
| | 47 | toolchain which can be used to compile modules for the motorola kernel, I have |
| | 48 | also uploaded a precompiled version of the module at |
| | 49 | http://rmdir.de/~michael/ms2-fixes/debounce.ko |
| | 50 | |
| | 51 | This version should work at least on MS2 2.2.16 and MS2 2.4.24 (which I am |
| | 52 | using), as I have built it against the 2.2.16 kernel sources (which are the |
| | 53 | only ones I can find) |
| | 54 | |
| | 55 | To use this module, you need a rooted phone. Copy the module to /tmp and run |
| | 56 | "insmod /tmp/debounce.ko". |
| | 57 | After that, you should see the following output in "dmesg": |
| | 58 | [CODE] |
| | 59 | <6>[ 1226.493377] Searching for gpio-event... |
| | 60 | <6>[ 1226.493804] Found it! |
| | 61 | <6>[ 1226.494079] And there is a sholes-keypad connected... |
| | 62 | <6>[ 1226.494842] settle_time: 40000 |
| | 63 | <6>[ 1226.495117] poll_time: 20000000 |
| | 64 | <6>[ 1226.495391] debounce_delay: 0 |
| | 65 | <6>[ 1226.495635] Activating debounce! |
| | 66 | <6>[ 1226.496917] debounce_delay: 5000000 |
| | 67 | [/CODE] |
| | 68 | |
| | 69 | Please test this module and see if it fixes your keyboard problems. (I have |
| | 70 | only slight double-presses, which are not really reproducible (but I had none |
| | 71 | since activating the debouncing)). I would be happy to hear that it works for |
| | 72 | other people, too. |
| | 73 | |
| | 74 | Thanks Motorola for making our lives so easy with a locked bootloader! |
| | 75 | |
| | 76 | Michael Gernoth <michael@gernoth.net> |
projects / ms2-fixes / blame_incremental