linux-kernel - Re: [PATCH v2 01/11] HID: hid-input: export hidinput_calc_abs

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Date:	Tue, 30 Oct 2012 11:04:36 +0100
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Henrik Rydberg <rydberg@...omail.se>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/11] HID: hid-input: export hidinput_calc_abs_res

Hi Henrik,

first thanks for the full review of the patch series.

If you think it's better, I'll split the patch in 2 to put aside the
DIV_ROUND_CLOSEST.

Cheers,
Benjamin

On Mon, Oct 29, 2012 at 7:57 PM, Henrik Rydberg <rydberg@...omail.se> wrote:
> Hi Benjamin,
>
>> Exporting this function allows us to calculate the resolution in third
>> party drivers like hid-multitouch.
>> This patch also complete the function with additional valid axes.
>>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
>> ---
>
> Nice, but please see comment below.
>
>>  drivers/hid/hid-input.c      | 11 +++++++++--
>>  drivers/hid/hid-multitouch.c |  1 +
>>  include/linux/hid.h          |  1 +
>>  3 files changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
>> index d917c0d..1b0adc3 100644
>> --- a/drivers/hid/hid-input.c
>> +++ b/drivers/hid/hid-input.c
>> @@ -208,7 +208,7 @@ static int hidinput_setkeycode(struct input_dev *dev,
>>   * Only exponent 1 length units are processed. Centimeters and inches are
>>   * converted to millimeters. Degrees are converted to radians.
>>   */
>> -static __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
>> +__s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
>>  {
>>       __s32 unit_exponent = field->unit_exponent;
>>       __s32 logical_extents = field->logical_maximum -
>> @@ -229,6 +229,12 @@ static __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
>>       case ABS_X:
>>       case ABS_Y:
>>       case ABS_Z:
>> +     case ABS_MT_POSITION_X:
>> +     case ABS_MT_POSITION_Y:
>> +     case ABS_MT_TOOL_X:
>> +     case ABS_MT_TOOL_Y:
>> +     case ABS_MT_TOUCH_MAJOR:
>> +     case ABS_MT_TOUCH_MINOR:
>>               if (field->unit == 0x11) {              /* If centimeters */
>>                       /* Convert to millimeters */
>>                       unit_exponent += 1;
>> @@ -281,8 +287,9 @@ static __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
>>       }
>>
>>       /* Calculate resolution */
>> -     return logical_extents / physical_extents;
>> +     return DIV_ROUND_CLOSEST(logical_extents, physical_extents);
>
> This line might be best left alone; if the round-off matters, you now
> risk regressing a carefully tuned userland.
>
>>  }
>> +EXPORT_SYMBOL_GPL(hidinput_calc_abs_res);
>>
>>  #ifdef CONFIG_HID_BATTERY_STRENGTH
>>  static enum power_supply_property hidinput_battery_props[] = {
>> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
>> index c97011c..375a38d 100644
>> --- a/drivers/hid/hid-multitouch.c
>> +++ b/drivers/hid/hid-multitouch.c
>> @@ -298,6 +298,7 @@ static void set_abs(struct input_dev *input, unsigned int code,
>>       int fmax = field->logical_maximum;
>>       int fuzz = snratio ? (fmax - fmin) / snratio : 0;
>>       input_set_abs_params(input, code, fmin, fmax, fuzz, 0);
>> +     input_abs_set_res(input, code, hidinput_calc_abs_res(field, code));
>>  }
>>
>>  static void mt_store_field(struct hid_usage *usage, struct mt_device *td,
>> diff --git a/include/linux/hid.h b/include/linux/hid.h
>> index 7e1f37d..9edb06c 100644
>> --- a/include/linux/hid.h
>> +++ b/include/linux/hid.h
>> @@ -743,6 +743,7 @@ int hid_input_report(struct hid_device *, int type, u8 *, int, int);
>>  int hidinput_find_field(struct hid_device *hid, unsigned int type, unsigned int code, struct hid_field **field);
>>  struct hid_field *hidinput_get_led_field(struct hid_device *hid);
>>  unsigned int hidinput_count_leds(struct hid_device *hid);
>> +__s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code);
>>  void hid_output_report(struct hid_report *report, __u8 *data);
>>  struct hid_device *hid_allocate_device(void);
>>  struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id);
>> --
>> 1.7.11.7
>>
>
> Thanks,
> Henrik
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