Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753499Ab2KMHn0 (ORCPT ); Tue, 13 Nov 2012 02:43:26 -0500 Received: from cantor2.suse.de ([195.135.220.15]:40296 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751347Ab2KMHnZ (ORCPT ); Tue, 13 Nov 2012 02:43:25 -0500 Date: Tue, 13 Nov 2012 08:43:19 +0100 (CET) From: Jiri Kosina To: Benjamin Tissoires Cc: Dmitry Torokhov , Henrik Rydberg , Stephane Chatty , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 03/13] HID: core: fix unit exponent parsing In-Reply-To: <1352306256-12180-4-git-send-email-benjamin.tissoires@gmail.com> Message-ID: References: <1352306256-12180-1-git-send-email-benjamin.tissoires@gmail.com> <1352306256-12180-4-git-send-email-benjamin.tissoires@gmail.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3919 Lines: 120 On Wed, 7 Nov 2012, Benjamin Tissoires wrote: > HID spec details special values for the HID field unit exponent. > Basically, the range [0x8..0xf] correspond to [-8..-1], so this is > a standard two's complement on a half-byte. > > Signed-off-by: Benjamin Tissoires Acked-by: Jiri Kosina > --- > drivers/hid/hid-core.c | 16 +++++++++++++++- > drivers/hid/hid-input.c | 13 +++++++++---- > include/linux/hid.h | 1 + > 3 files changed, 25 insertions(+), 5 deletions(-) > > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c > index 3d0da29..9da3007 100644 > --- a/drivers/hid/hid-core.c > +++ b/drivers/hid/hid-core.c > @@ -315,6 +315,7 @@ static s32 item_sdata(struct hid_item *item) > > static int hid_parser_global(struct hid_parser *parser, struct hid_item *item) > { > + __u32 raw_value; > switch (item->tag) { > case HID_GLOBAL_ITEM_TAG_PUSH: > > @@ -365,7 +366,14 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item) > return 0; > > case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT: > - parser->global.unit_exponent = item_sdata(item); > + /* Units exponent negative numbers are given through a > + * two's complement. > + * See "6.2.2.7 Global Items" for more information. */ > + raw_value = item_udata(item); > + if (!(raw_value & 0xfffffff0)) > + parser->global.unit_exponent = hid_snto32(raw_value, 4); > + else > + parser->global.unit_exponent = raw_value; > return 0; > > case HID_GLOBAL_ITEM_TAG_UNIT: > @@ -865,6 +873,12 @@ static s32 snto32(__u32 value, unsigned n) > return value & (1 << (n - 1)) ? value | (-1 << n) : value; > } > > +s32 hid_snto32(__u32 value, unsigned n) > +{ > + return snto32(value, n); > +} > +EXPORT_SYMBOL_GPL(hid_snto32); > + > /* > * Convert a signed 32-bit integer to a signed n-bit integer. > */ > diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c > index 67044f3..7015080 100644 > --- a/drivers/hid/hid-input.c > +++ b/drivers/hid/hid-input.c > @@ -192,7 +192,6 @@ static int hidinput_setkeycode(struct input_dev *dev, > return -EINVAL; > } > > - > /** > * hidinput_calc_abs_res - calculate an absolute axis resolution > * @field: the HID report field to calculate resolution for > @@ -235,17 +234,23 @@ __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code) > case ABS_MT_TOOL_Y: > case ABS_MT_TOUCH_MAJOR: > case ABS_MT_TOUCH_MINOR: > - if (field->unit == 0x11) { /* If centimeters */ > + if (field->unit & 0xffffff00) /* Not a length */ > + return 0; > + unit_exponent += hid_snto32(field->unit >> 4, 4) - 1; > + switch (field->unit & 0xf) { > + case 0x1: /* If centimeters */ > /* Convert to millimeters */ > unit_exponent += 1; > - } else if (field->unit == 0x13) { /* If inches */ > + break; > + case 0x3: /* If inches */ > /* Convert to millimeters */ > prev = physical_extents; > physical_extents *= 254; > if (physical_extents < prev) > return 0; > unit_exponent -= 1; > - } else { > + break; > + default: > return 0; > } > break; > diff --git a/include/linux/hid.h b/include/linux/hid.h > index 9edb06c..a110a3e 100644 > --- a/include/linux/hid.h > +++ b/include/linux/hid.h > @@ -754,6 +754,7 @@ int hid_connect(struct hid_device *hid, unsigned int connect_mask); > void hid_disconnect(struct hid_device *hid); > const struct hid_device_id *hid_match_id(struct hid_device *hdev, > const struct hid_device_id *id); > +s32 hid_snto32(__u32 value, unsigned n); > > /** > * hid_map_usage - map usage input bits > -- > 1.7.11.7 > -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/