Re: [PATCH 1/5] Input: Add input_copy_abs() function

[Hans de Goede <hdegoede@redhat.com>]

Hi Dmitry,

Thank you for your review of this patch series; and sorry for
being so slow in getting back to you on this.

On 12/13/21 05:58, Dmitry Torokhov wrote:
> Hi Hans,
> 
> On Sun, Dec 12, 2021 at 01:42:38PM +0100, Hans de Goede wrote:
>> Add a new helper function to copy absinfo from one input_dev to
>> another input_dev.
>>
>> This is useful to e.g. setup a pen/stylus input-device for combined
>> touchscreen/pen hardware where the pen uses the same coordinates as
>> the touchscreen.
>>
>> Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>  drivers/input/input.c | 34 ++++++++++++++++++++++++++++++++++
>>  include/linux/input.h |  2 ++
>>  2 files changed, 36 insertions(+)
>>
>> diff --git a/drivers/input/input.c b/drivers/input/input.c
>> index ccaeb2426385..60f3eb38906f 100644
>> --- a/drivers/input/input.c
>> +++ b/drivers/input/input.c
>> @@ -526,6 +526,40 @@ void input_set_abs_params(struct input_dev *dev, unsigned int axis,
>>  }
>>  EXPORT_SYMBOL(input_set_abs_params);
>>  
>> +/**
>> + * input_copy_abs - Copy absinfo from one input_dev to another
>> + * @dst: Destination input device to copy the abs settings to
>> + * @dst_axis: ABS_* value selecting the destination axis
>> + * @src: Source input device to copy the abs settings from
>> + * @src_axis: ABS_* value selecting the source axis
>> + *
>> + * Set absinfo for the selected destination axis by copying it from
>> + * the specified source input device's source axis.
>> + * This is useful to e.g. setup a pen/stylus input-device for combined
>> + * touchscreen/pen hardware where the pen uses the same coordinates as
>> + * the touchscreen.
>> + */
>> +void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
>> +		    const struct input_dev *src, unsigned int src_axis)
>> +{
>> +	/*
>> +	 * input_alloc_absinfo() may have failed for the source. Our caller is
>> +	 * expected to catch this when registering the input devices, which may
>> +	 * happen after the input_copy_abs() call.
>> +	 */
>> +	if (!src->absinfo)
>> +		return;
> 
> I'd probably check if source device actually declared EV_ABS/src_axis
> and yelled loudly (WARN?) in such case.

Ack, I will add this for v2.

> 
>> +
>> +	input_alloc_absinfo(dst);
>> +	if (!dst->absinfo)
>> +		return;
>> +
>> +	dst->absinfo[dst_axis] = src->absinfo[src_axis];
>> +
>> +	__set_bit(EV_ABS, dst->evbit);
>> +	__set_bit(dst_axis, dst->absbit);
> 
> input_set_capability() ?

Ack.

Regards,

Hans



> 
>> +}
>> +EXPORT_SYMBOL(input_copy_abs);
> 
> Thanks.
>