On Wed, 12 Dec 2012 10:58:56 -0800, Dmitry Torokhov <[email protected]> wrote :
> On Wed, Dec 12, 2012 at 10:58:29AM +0100, Anisse Astier wrote: > > On Tue, 11 Dec 2012 20:27:26 +0200, Maxim Mikityanskiy > > <[email protected]> wrote : > > > > > 2012/12/11 Anisse Astier <[email protected]>: > > > > On Tue, 11 Dec 2012 19:07:51 +0200, Maxim Mikityanskiy > > > > <[email protected]> wrote : > > > > > > > >> >> @@ -169,11 +169,15 @@ static void msi_wmi_notify(u32 value, void > > > >> >> *context) > > > >> >> pr_debug("Eventcode: 0x%x\n", eventcode); > > > >> >> key = > > > >> >> sparse_keymap_entry_from_scancode(msi_wmi_input_dev, > > > >> >> eventcode); > > > >> >> - if (key) { > > > >> >> + if (!key) { > > > >> >> + pr_info("Unknown key pressed - %x\n", > > > >> >> eventcode); > > > >> >> + goto msi_wmi_notify_exit; > > > >> >> + } > > > >> >> + if (quirk_last_pressed) { > > > >> >> + size_t key_index = key - msi_wmi_keymap; > > > >> > Do you mean key->code - MSI_SCANCODE_BASE ? I'm not sure I > > > >> > understand the > > > >> > intent here otherwise. > > > >> > > > >> msi_wmi_keymap is array of 'struct key_entry', i.e. pointer to array's > > > >> first item. key is a pointer to some array's item. So 'key - > > > >> msi_wmi_keymap' is a difference between pointers, i.e. index of key in > > > >> msi_wmi_keymap. > > > >> > > > >> I do pointer arithmetic here because in patch 12 I add some new > > > >> scancodes, and holes appear in scancode sequence, so we can't just use > > > >> 'key->code - MSI_SCANCODE_BASE' to get item index in array. > > > > > > > > Oh, I see. This is very clever, but a bit too clever. You have no > > > > guarantee, that sparse_keymap_entry_from_scancode will give you a > > > > pointer > > > > to *your* key_entry. In fact, it doesn't. > > > > > > > > In sparse_keymap_setup (drivers/input/sparse-keymap.c), the keymap > > > > array(msi_wmi_keymap) is mempcy-ed, at line 187 (kernel ~3.7). So if you > > > > want to use this method, you might need to re-compute the index by > > > > iterating over the elements and comparing key->code for each. > > > > > > Oops, I'm sorry, I was looking only into > > > sparse_keymap_entry_from_scancode() and I didn't discover the fact > > > that dev->keycode is not equal to msi_wmi_keymap. I just wanted to > > > avoid iterating through the array second time. Also, can I use > > > msi_wmi_input_dev->keycode instead of msi_wmi_keymap as array base? > > > input_dev::keycode field is documented at include/linux/input.h:62. > > > > As I said, you could iterate over msi_wmi_keymap and compare key->code to > > each keycode to compute key_index each time. > > > > > > > > It's strange that I didn't get a crash or data corruption on my system > > > when I forced usage of last_pressed for my laptop, loaded this module > > > and tried to press keys. > > > > > > It's very unconvenient that struct key_entry does not have some field > > > for driver-specific extra data. In such field we could store index in > > > last_pressed or event last press time. But we haven't such field. > > > > If that's really needed, such field could be added. Cc-ing Dmitry > > Torokhov to ask what he thinks about altering the sparse keymap API for > > this use case, ie having per key_entry variables to store information, > > here used for debouncing. > > Previously the keymap was contiguous, but we're adding new keys, so it'll > > really be sparse, so we can't use the same trick substraction trick. > > A different question - do you really need to store times for all > possible keys or you actually need to know just the last key that was > pressed? Not at all. This isn't a gamepad, so I think this quirk could be simplified by just storing the last trigger time overall, not per-key trigger time. 1 key every 50ms means you can still input 20 keys per second, which isn't bad. Maxim, if you make this modification it would simplify your patch even further. Cc-ing original author Thomas Renninger for feedback. Anisse -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
