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Subject: Re[2]: [PATCH] input: gpio-keys - optimize wakeup sequence.
Reply-To: abhi1.singh@samsung.com
Sender: Abhishek Kumar Singh <abhi1.singh@samsung.com>
From:   Abhishek Kumar Singh <abhi1.singh@samsung.com>
To:     "dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>
CC:     "robh@kernel.org" <robh@kernel.org>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        SRI-N IT Security <sri-n.itsec@samsung.com>
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Message-ID: <20231107082901epcms5p80c830aecfe50bfb12b661defad701149@epcms5p8>
Date:   Tue, 07 Nov 2023 13:59:01 +0530
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        <CGME20231017103415epcms5p2f8f5b28a8f5d71055622b82f71b0fc93@epcms5p8>
Precedence: bulk

Dear Dmitry,=20

Greetings=21=21=21

Thank you so much for your response.

I checked in detailed again and observed the below points, please help to r=
eview=20
and approve it.


There is ISR =22gpio_keys_gpio_isr=22 which is called when the key state is=
 1 i.e.=20
key pressed.
Therefore modified code will not impact on the existing driver code.

//For key pressed event:
<3>=5B  549.180072=5D I=5B0:      swapper/0:    0=5D gpio_keys_gpio_isr
<3>=5B  549.196126=5D  =5B1:    kworker/1:1:   78=5D gpio_keys_gpio_work_fu=
nc
<3>=5B  549.196198=5D  =5B1:    kworker/1:1:   78=5D gpio-keys soc:gpio_key=
s: gpio_keys_gpio_report_event key =3D 115, value =3D 1


Performance:

I have calculated the differece between entry & exit time=20
with modified and without modified code and observed that=20
0.3ms extra computation time in current scenario in each entry/exit time.

Because below APIs will not be called in every resume functions:

1. static void gpio_keys_report_state(struct gpio_keys_drvdata *ddata)
2. static void gpio_keys_gpio_report_event(struct gpio_button_data *bdata)
3. gpiod_get_value_cansleep(bdata->gpiod);
4. input_event(input, type, *bdata->code, state);
5. input_sync(input)

So we can save 0.3ms computation time, resume operations will faster and sa=
ve battery as well.


With changes:

Line   311960: 07-18 16:50:09.359  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state exit 2023-07-18 11:20:37.573207725 UTC
Line   312626: 07-18 16:50:42.123  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state enrty 2023-07-18 11:22:20.503579404 UTC
Line   312627: 07-18 16:50:42.123  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state exit 2023-07-18 11:22:20.503656644 UTC
Line   313301: 07-18 16:52:24.182  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state enrty 2023-07-18 11:22:33.865626325 UTC
Line   313302: 07-18 16:52:24.182  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state exit 2023-07-18 11:22:33.865724502 UTC
Line   313572: 07-18 16:52:35.111  root     0     0 I =5B1:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state enrty 2023-07-18 11:22:37.678468979 UTC
Line   313573: 07-18 16:52:35.111  root     0     0 I =5B1:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state exit 2023-07-18 11:22:37.678566167 UTC
Line   314209: 07-18 16:52:43.598  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state enrty 2023-07-18 11:23:05.925340634 UTC
Line   314210: 07-18 16:52:43.598  root     0     0 I =5B0:   Binder:699_1:=
20972=5D PM: gpio_keys_report_state exit 2023-07-18 11:23:05.925439384 UTC


Without changes:

Line   372095: 07-18 16:10:24.250  root     0     0 I =5B1:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state exit 2023-07-18 10:43:38.592548979 UTC
Line   372344: 07-18 16:13:45.439  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state enrty 2023-07-18 10:44:11.589164226 UTC
Line   372346: 07-18 16:13:45.439  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state exit 2023-07-18 10:44:11.589514955 UTC
Line   372573: 07-18 16:14:13.414  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state enrty 2023-07-18 10:44:22.606227138 UTC
Line   372575: 07-18 16:14:13.414  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state exit 2023-07-18 10:44:22.606490107 UTC
Line   372944: 07-18 16:14:26.732  root     0     0 I =5B1:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state enrty 2023-07-18 10:44:29.024121927 UTC
Line   372946: 07-18 16:14:26.732  root     0     0 I =5B1:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state exit 2023-07-18 10:44:29.024528958 UTC
Line   373181: 07-18 16:14:30.790  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state enrty 2023-07-18 10:44:30.904866770 UTC
Line   373183: 07-18 16:14:30.790  root     0     0 I =5B0:   Binder:702_2:=
18137=5D PM: gpio_keys_report_state exit 2023-07-18 10:44:30.905126353 UTC


Thanks and Regards,
Abhishek Kumar Singh
Sr. Chief Engineer, Samsung Electronics, Noida-India


=C2=A0=0D=0A---------=C2=A0Original=20Message=C2=A0---------=0D=0ASender=C2=
=A0:=20dmitry.torokhov=40gmail.com=20<dmitry.torokhov=40gmail.com>=0D=0ADat=
e=C2=A0=20=C2=A0:=202023-10-29=2007:42=20(GMT+5:30)=0D=0ATitle=C2=A0=20:=20=
Re:=20=5BPATCH=5D=20input:=20gpio-keys=20-=20optimize=20wakeup=20sequence.=
=0D=0ATo=20:=C2=A0Abhishek=20Kumar=20Singh<abhi1.singh=40samsung.com>=0D=0A=
CC=20:=C2=A0robh=40kernel.org<robh=40kernel.org>,=20linux-input=40vger.kern=
el.org<linux-input=40vger.kernel.org>,=20linux-kernel=40vger.kernel.org<lin=
ux-kernel=40vger.kernel.org>,=20SRI-N=20IT=20Security<sri-n.itsec=40samsung=
.com>=0D=0A=C2=A0=0D=0AHi=20Abhishek,=0D=0A=0D=0AOn=20Thu,=20Oct=2026,=2020=
23=20at=2011:23:20AM=20+0530,=20Abhishek=20Kumar=20Singh=20wrote:=0D=0A>=20=
Dear=20Mr.=20Dmitry,=0D=0A>=20Greetings=21=0D=0A>=C2=A0=0D=0A>=C2=A0=0D=0A>=
=20The=20patch=20removes=20unused=20many=20APIs=20call=20chain=20for=20ever=
y=20suspend/resume=20of=20the=20device=C2=A0=0D=0A>=20if=20no=20key=20press=
=20event=20triggered.=0D=0A>=C2=A0=0D=0A>=C2=A0=0D=0A>=20There=20is=20a=20c=
all=20back=20function=20gpio_keys_resume()=20called=20for=0D=0A>=20every=20=
suspend/resume=20of=20the=20device.=20and=20whenever=20this=20function=20ca=
lled,=20it=20is=0D=0A>=20reading=20the=20status=20of=20the=20key.=20And=20g=
pio_keys_resume()=20API=20further=20calls=20the=0D=0A>=20below=20chain=20of=
=20API=20irrespective=20of=20key=20press=20event=0D=0A>=C2=A0=0D=0A>=C2=A0=
=0D=0A>=20APIs=20call=20chain:=0D=0A>=20static=20void=20gpio_keys_report_st=
ate(struct=20gpio_keys_drvdata=20*ddata)=0D=0A>=20static=20void=20gpio_keys=
_gpio_report_event(struct=20gpio_button_data=20*bdata)=0D=0A>=20gpiod_get_v=
alue_cansleep(bdata->gpiod);=0D=0A>=20input_event(input,=20type,=20*bdata->=
code,=20state);=0D=0A>=20input_sync(input);=0D=0A>=C2=A0=0D=0A>=C2=A0=0D=0A=
>=20The=20patch=20avoid=20the=20above=20APIs=20call=20chain=20if=20there=20=
is=20no=20key=20press=20event=20triggered.=0D=0A>=20It=20will=20save=20the=
=20device=20computational=20resources,=20power=20resources=20and=20optimize=
=20the=20suspend/resume=20time=0D=0A=0D=0AUnfortunately=20it=20also=20break=
s=20the=20driver=20as=20button->value=20does=20not=20hold=0D=0Athe=20curren=
t=20state=20of=20the=20GPIO=20but=20rather=20set=20one=20via=20device=20tre=
e=20so=20that=0D=0Athe=20driver=20can=20use=20that=20value=20when=20sending=
=20EV_ABS=20events.=20So=20with=0D=0Atypical=20GPIO-backed=20keys=20or=20bu=
ttons=20you=20change=20results=20in=20no=20events=0D=0Areported=20on=20resu=
me.=0D=0A=0D=0AI=20also=20wonder=20what=20kind=20of=20measurements=20you=20=
did=20on=20improvements=20to=0D=0Asuspend/resume=20time=20with=20your=20cha=
nge.=0D=0A=0D=0AThanks.=0D=0A=0D=0A--=C2=A0=0D=0ADmitry=0D=0A=0D=0A=C2=A0=
=0D=0AThanks=20and=20Regards,=0D=0A=C2=A0=C2=A0