Hi Henrik, Please see my comments inline. Thanks, Roderick On Thu, Oct 27, 2016 at 3:46 PM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: > Hi Roderick, > >> Pointer emulation is undesired on drivers, which didn't request this >> capability like the hid-sony driver for the Dualshock 4. This gamepad already >> reports ABS_X / ABS_Y for gamepad stick purposes. Pointer emulation would >> inject touchpad values into these sticks, which is undesired. >> >> This patch checks the flags INPUT_MT_POINTER / INPUT_MT_DIRECT from within >> input_mt_sync_frame to only allow pointer emulation when the feature was >> requested by the driver as the flags were set in input_mt_init_slots. > > So why call input_mt_sync_frame() in the first place? > > The existing drivers that use ABS_X / ABS_Y independently do not call that > function. It seems your recent hid-sony patches adds it, which leads to broken > behavior. As part of the review, it was recommended to call input_mt_sync_frame to make sure we don't lose certain events. Later on after more validation, we noticed this issue which we weren't aware of. >> --- >> drivers/input/input-mt.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c >> index a1bbec9..30c8128 100644 >> --- a/drivers/input/input-mt.c >> +++ b/drivers/input/input-mt.c >> @@ -305,7 +305,8 @@ void input_mt_sync_frame(struct input_dev *dev) >> if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT)) >> use_count = true; >> >> - input_mt_report_pointer_emulation(dev, use_count); >> + if (mt->flags & (INPUT_MT_POINTER | INPUT_MT_DIRECT)) >> + input_mt_report_pointer_emulation(dev, use_count); >> >> mt->frame++; >> } >> > > That said, I am not against this patch at all, I think it is good, but the > commit message should address the effect on the large number of existing drivers > that use this functionality. Is any of them affected by this patch? As you > probably know, we do not like to break userspace. > > From what I can see, only hid-multitouch (Benjamin?) and hid-sony use > input_mt_init_slots() in such a way that MT_POINTER or MT_DIRECT cannot be > directly inferred. So if Benjamin sees no issues with this, I am ok with the change. > > Thanks, > Henrik > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
