From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH v3 11/12] msi-wmi: Introduced quirk_last_pressed Date: Wed, 12 Dec 2012 10:58:56 -0800 Message-ID: <20121212185856.GA10583@core.coreip.homeip.net> References: <1354888162-12109-1-git-send-email-maxtram95@gmail.com> <1354888162-12109-12-git-send-email-maxtram95@gmail.com> <20121211172930.0490654a@destiny.ordissimo> <20121211183914.460ed479@destiny.ordissimo> <20121212105829.15819617@destiny.ordissimo> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:59307 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753949Ab2LLS7B (ORCPT ); Wed, 12 Dec 2012 13:59:01 -0500 Received: by mail-pa0-f46.google.com with SMTP id bh2so868709pad.19 for ; Wed, 12 Dec 2012 10:59:00 -0800 (PST) Content-Disposition: inline In-Reply-To: <20121212105829.15819617@destiny.ordissimo> Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Anisse Astier Cc: Maxim Mikityanskiy , "platform-driver-x86@vger.kernel.org" , joeyli On Wed, Dec 12, 2012 at 10:58:29AM +0100, Anisse Astier wrote: > On Tue, 11 Dec 2012 20:27:26 +0200, Maxim Mikityanskiy wrote : > > > 2012/12/11 Anisse Astier : > > > On Tue, 11 Dec 2012 19:07:51 +0200, Maxim Mikityanskiy 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? Thanks. -- Dmitry