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SubjectRe: [PATCH 06/25] HID: multitouch: optimize FlatFrog panels
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On Mon, Jan 28, 2013 at 4:10 PM, Henrik Rydberg <rydberg@euromail.se> wrote:
> Hi Benjamin,
>
>> Relying on ALWAYS_VALID enhance a little the processing time of
>> the events.
>>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
>> ---
>> drivers/hid/hid-multitouch.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> Is there a measurement backing up this claim? I suspect
> micro-optimizations of this kind drowns completely along the rather
> long way from device, via malloc and loops, to the input core.

No, the measure I made for this are roughly the same. It's purely
micro-optimization, and yes, mallocs must kill the processing time.
However, the purpose of this patch and the others entitled 'optimize
XXX' is to show that I did not invented the new default class. My true
objective is to remove all the quirks related to the 'valid'
information in order to have a driver as universal as possible and to
be able to clean it up.

> Considering the must-be-tested-for-regression risk on top of that,
> this patch falls far below what is worth doing, IMHO.

It _has_ been tested. I got the HID traces from FlatFrog and either
they use different firmwares with different processing in their
devices, the kernel processing is good.

Cheers,
Benjamin

>
>> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
>> index 5a886bd..7dfe891 100644
>> --- a/drivers/hid/hid-multitouch.c
>> +++ b/drivers/hid/hid-multitouch.c
>> @@ -229,8 +229,9 @@ static struct mt_class mt_classes[] = {
>> },
>>
>> { .name = MT_CLS_FLATFROG,
>> - .quirks = MT_QUIRK_NOT_SEEN_MEANS_UP |
>> - MT_QUIRK_NO_AREA,
>> + .quirks = MT_QUIRK_ALWAYS_VALID |
>> + MT_QUIRK_NO_AREA |
>> + MT_QUIRK_CONTACT_CNT_ACCURATE,
>> .sn_move = 2048,
>> .maxcontacts = 40,
>> },
>> --
>> 1.8.1
>>
>
> Thanks.
> Henrik


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