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Tue, 5 Aug 2025 17:52:45 +0000 (GMT) From: "Alim Akhtar" To: "'Konrad Dybcio'" , "'Manivannan Sadhasivam'" Cc: "'Krzysztof Kozlowski'" , "'Ram Kumar Dwivedi'" , , , , , , , , , , , , , , In-Reply-To: <87c37d65-5ab1-4443-a428-dc3592062cdc@oss.qualcomm.com> Subject: RE: [PATCH 2/3] arm64: dts: qcom: sa8155: Add gear and rate limit properties to UFS Date: Tue, 5 Aug 2025 23:22:44 +0530 Message-ID: <061d01dc0631$c1766c00$44634400$@samsung.com> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Content-Language: en-us Thread-Index: AQGIhTOigFb9OSA/zLmmRAowhNFqCwJZOa1wAh4tdyIBxgZwxgI/ArKTAmrI7FMCp5bdBAEsJt2OAdY+bWECqijPQgIPv58TAQlCtSUCbRSB8rQ1S7YA X-CMS-MailID: 20250805175248epcas5p1ac576a2bfa05ed08b0c6a35aaac46505 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250805170638epcas5p4cb0cc78c5b5d77072cec547380b9f03d References: <2a3c8867-7745-4f0a-8618-0f0f1bea1d14@kernel.org> <1701ec08-21bc-45b8-90bc-1cd64401abd8@kernel.org> <2nm7xurqgzrnffustrsmswy2rbug6geadaho42qlb7tr2jirlr@uw5gaery445y> <11ea828a-6d35-4ac6-a207-0284870c28fc@oss.qualcomm.com> <061b01dc062d$25c47800$714d6800$@samsung.com> <061c01dc062f$70ec34b0$52c49e10$@samsung.com> <87c37d65-5ab1-4443-a428-dc3592062cdc@oss.qualcomm.com> > -----Original Message----- > From: Konrad Dybcio > Sent: Tuesday, August 5, 2025 11:10 PM > To: Alim Akhtar ; 'Manivannan Sadhasivam' > > Cc: 'Krzysztof Kozlowski' ; 'Ram Kumar Dwivedi' > ; avri.altman=40wdc.com; > bvanassche=40acm.org; robh=40kernel.org; krzk+dt=40kernel.org; > conor+dt=40kernel.org; andersson=40kernel.org; konradybcio=40kernel.org; > James.Bottomley=40hansenpartnership.com; martin.petersen=40oracle.com; > agross=40kernel.org; linux-arm-msm=40vger.kernel.org; linux- > scsi=40vger.kernel.org; devicetree=40vger.kernel.org; linux- > kernel=40vger.kernel.org > Subject: Re: =5BPATCH 2/3=5D arm64: dts: qcom: sa8155: Add gear and rate = limit > properties to UFS >=20 > On 8/5/25 7:36 PM, Alim Akhtar wrote: > > > > > >> -----Original Message----- > >> From: 'Manivannan Sadhasivam' > >> Sent: Tuesday, August 5, 2025 10:52 PM > >> To: Alim Akhtar > >> Cc: 'Konrad Dybcio' ; 'Krzysztof > >> Kozlowski' ; 'Ram Kumar Dwivedi' > >> ; avri.altman=40wdc.com; > bvanassche=40acm.org; > >> robh=40kernel.org; krzk+dt=40kernel.org; > >> conor+dt=40kernel.org; andersson=40kernel.org; konradybcio=40kernel.or= g; > >> James.Bottomley=40hansenpartnership.com; > martin.petersen=40oracle.com; > >> agross=40kernel.org; linux-arm-msm=40vger.kernel.org; linux- > >> scsi=40vger.kernel.org; devicetree=40vger.kernel.org; linux- > >> kernel=40vger.kernel.org > >> Subject: Re: =5BPATCH 2/3=5D arm64: dts: qcom: sa8155: Add gear and ra= te > >> limit properties to UFS > >> > >> On Tue, Aug 05, 2025 at 10:49:45PM GMT, Alim Akhtar wrote: > >>> > >>> > >>>> -----Original Message----- > >>>> From: Konrad Dybcio > >>>> Sent: Tuesday, August 5, 2025 10:36 PM > >>>> To: Manivannan Sadhasivam > >>>> Cc: Krzysztof Kozlowski ; Ram Kumar Dwivedi > >>>> ; alim.akhtar=40samsung.com; > >>>> avri.altman=40wdc.com; bvanassche=40acm.org; robh=40kernel.org; > >>>> krzk+dt=40kernel.org; conor+dt=40kernel.org; andersson=40kernel.org; > >>>> konradybcio=40kernel.org; James.Bottomley=40hansenpartnership.com; > >>>> martin.petersen=40oracle.com; agross=40kernel.org; linux-arm- > >>>> msm=40vger.kernel.org; linux-scsi=40vger.kernel.org; > >>>> devicetree=40vger.kernel.org; linux-kernel=40vger.kernel.org > >>>> Subject: Re: =5BPATCH 2/3=5D arm64: dts: qcom: sa8155: Add gear and > >>>> rate limit properties to UFS > >>>> > >>>> On 8/5/25 6:55 PM, Manivannan Sadhasivam wrote: > >>>>> On Tue, Aug 05, 2025 at 03:16:33PM GMT, Konrad Dybcio wrote: > >>>>>> On 8/1/25 2:19 PM, Manivannan Sadhasivam wrote: > >>>>>>> On Fri, Aug 01, 2025 at 11:12:42AM GMT, Krzysztof Kozlowski > wrote: > >>>>>>>> On 01/08/2025 11:10, Ram Kumar Dwivedi wrote: > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> On 01-Aug-25 1:58 PM, Manivannan Sadhasivam wrote: > >>>>>>>>>> On Thu, Jul 24, 2025 at 09:48:53AM GMT, Krzysztof Kozlowski > >> wrote: > >>>>>>>>>>> On 22/07/2025 18:11, Ram Kumar Dwivedi wrote: > >>>>>>>>>>>> Add optional limit-hs-gear and limit-rate properties to the > >>>>>>>>>>>> UFS node to support automotive use cases that require > >>>>>>>>>>>> limiting the maximum Tx/Rx HS gear and rate due to > hardware > >> constraints. > >>>>>>>>>>> > >>>>>>>>>>> What hardware constraints? This needs to be clearly > >> documented. > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Ram, both Krzysztof and I asked this question, but you never > >>>>>>>>>> bothered to reply, but keep on responding to other comments. > >>>>>>>>>> This won't help you to get this series merged in any form. > >>>>>>>>>> > >>>>>>>>>> Please address *all* review comments before posting next > >> iteration. > >>>>>>>>> > >>>>>>>>> Hi Mani, > >>>>>>>>> > >>>>>>>>> Apologies for the delay in responding. > >>>>>>>>> I had planned to explain the hardware constraints in the next > >>>> patchset=E2=80=99s=20commit=20message,=20which=20is=20why=20I=20didn= =E2=80=99t=20reply=20earlier.=0D=0A>=20>>>>>>>>>=0D=0A>=20>>>>>>>>>=20To=20= clarify:=20the=20limitations=20are=20due=20to=20customer=20board=20designs,= =0D=0A>=20>>>>>>>>>=20not=20our=0D=0A>=20>>>>=20SoC.=20Some=20boards=20can'= t=20support=20higher=20gear=20operation,=20hence=20the=0D=0A>=20>>>>=20need= =20for=20optional=20limit-hs-gear=20and=20limit-rate=20properties.=0D=0A>= =20>>>>>>>>>=0D=0A>=20>>>>>>>>=0D=0A>=20>>>>>>>>=20That's=20vague=20and=20d= oes=20not=20justify=20the=20property.=20You=20need=20to=0D=0A>=20>>>>>>>>= =20document=20instead=20hardware=20capabilities=20or=20characteristic.=20Or= =0D=0A>=20>>>>>>>>=20explain=20why=20they=20cannot.=20With=20such=20form=20= I=20will=20object=20to=20your=0D=0A>=20>>>>>>>>=20next=0D=0A>=20>>>>=20patc= h.=0D=0A>=20>>>>>>>>=0D=0A>=20>>>>>>>=0D=0A>=20>>>>>>>=20I=20had=20an=20off= line=20chat=20with=20Ram=20and=20got=20clarified=20on=20what=20these=0D=0A>= =20>>>>>>>=20properties=0D=0A>=20>>>>=20are.=0D=0A>=20>>>>>>>=20The=20probl= em=20here=20is=20not=20with=20the=20SoC,=20but=20with=20the=20board=20desig= n.=0D=0A>=20>>>>>>>=20On=20some=20Qcom=20customer=20designs,=20both=20the= =20UFS=20controller=20in=20the=0D=0A>=20>>>>>>>=20SoC=20and=20the=20UFS=20d= evice=20are=20capable=20of=20operating=20at=20higher=20gears=0D=0A>=20>>>>>= >>=20(say=0D=0A>=20>>=20G5).=0D=0A>=20>>>>>>>=20But=20due=20to=20board=20co= nstraints=20like=20poor=20thermal=20dissipation,=0D=0A>=20>>>>>>>=20routing= =20loss,=20the=20board=20cannot=20efficiently=20operate=20at=20the=20higher= =0D=0A>=20>>=20speeds.=0D=0A>=20>>>>>>>=0D=0A>=20>>>>>>>=20So=20the=20custo= mers=20wanted=20a=20way=20to=20limit=20the=20gear=20speed=20(say=20G3)=0D= =0A>=20>>>>>>>=20and=20rate=20(say=20Mode-A)=20on=20the=20specific=20board= =20DTS.=0D=0A>=20>>>>>>=0D=0A>=20>>>>>>=20I'm=20not=20necessarily=20saying= =20no,=20but=20have=20you=20explored=20sysfs=20for=20this?=0D=0A>=20>>>>>>= =0D=0A>=20>>>>>>=20I=20suppose=20it=20may=20be=20too=20late=20(if=20the=20d= river=20would=20e.g.=20init=20the=0D=0A>=20>>>>>>=20UFS=20at=20max=20gear/r= ate=20at=20probe=20time,=20it=20could=20cause=20havoc=20as=20it=0D=0A>=20>>= >>>>=20tries=20to=20load=20the=20userland)..=0D=0A>=20>>>>>>=0D=0A>=20>>>>>= =0D=0A>=20>>>>>=20If=20the=20driver=20tries=20to=20run=20with=20unsupported= =20max=20gear=20speed/mode,=0D=0A>=20>>>>>=20it=20will=20just=20crash=20wit= h=20the=20error=20spit.=0D=0A>=20>>>>=0D=0A>=20>>>>=20OK=0D=0A>=20>>>>=0D= =0A>=20>>>>=20just=20a=20couple=20related=20nits=20that=20I=20won't=20bothe= r=20splitting=20into=0D=0A>=20>>>>=20separate=20emails=0D=0A>=20>>>>=0D=0A>= =20>>>>=20rate=20(mode?=20I'm=20seeing=20both=20names)=20should=20probably= =20have=20dt-bindings=0D=0A>=20>>>>=20defines=20while=20gear=20doesn't=20ha= ve=20to=20since=20they're=20called=20G=0D=0A>=20>>>>=20anyway,=20wi= th=20the=20bindings=20description=20strongly=20discouraging=20use,=0D=0A>= =20>>>>=20unless=20absolutely=20necessary=20(e.g.=20in=20the=20situation=20= we=20have=20right=0D=0A>=20>>>>=20there)=0D=0A>=20>>>>=0D=0A>=20>>>>=20I'd= =20also=20assume=20the=20code=20should=20be=20moved=20into=20the=20ufs-comm= on=20code,=0D=0A>=20>>>>=20rather=20than=20making=20it=20ufs-qcom=20specifi= c=0D=0A>=20>>>>=0D=0A>=20>>>>=20Konrad=0D=0A>=20>>>=20Since=20this=20is=20a= =20board=20specific=20constrains=20and=20not=20a=20SoC=20properties,=0D=0A>= =20>>>=20have=20an=0D=0A>=20>>=20option=20of=20handling=20this=20via=20boot= loader=20is=20explored?=0D=0A>=20>>=0D=0A>=20>>=20Both=20board=20and=20SoC= =20specific=20properties=20*should*=20be=20described=20in=0D=0A>=20>>=20dev= icetree=20if=20they=20are=20purely=20describing=20the=20hardware.=0D=0A>=20= >>=0D=0A>=20>=20Agreed,=20what=20I=20understood=20from=20above=20conversati= on=20is=20that,=20we=20are=20try=0D=0A>=20>=20to=20solve=20a=20very=20*spec= ific*=20board=20problem=20here,=20this=20does=20not=20looks=20like=20a=0D= =0A>=20generic=20problem=20to=20me=20and=20probably=20should=20be=20handled= =20within=20the=20specific=0D=0A>=20driver.=0D=0A>=20=0D=0A>=20Introducing= =20generic=20solutions=20preemptively=20for=20problems=20that=20are=20simpl= e=20in=0D=0A>=20concept=20and=20can=20occur=20widely=20is=20good=20practice= =20(although=20it's=20sometimes=20hard=0D=0A>=20to=20gauge=20whether=20this= =20is=20a=20one-off),=20as=20if=20the=20issue=20spreads=20a=20generic=20sol= ution=0D=0A>=20will=20appear=20at=20some=20point,=20but=20we'll=20have=20to= =20keep=20supporting=20the=20odd=20ones=20as=0D=0A>=20well=0D=0A>=20=0D=0AO= k,=20=0D=0AI=20would=20prefer=20if=20we=20add=20a=20property=20which=20soun= ds=20like=20=22poor=20thermal=20dissipation=22=20or=20=0D=0A=22routing=20ch= annel=20loss=22=20rather=20than=20adding=20limiting=20UFS=20gear=20properti= es.=20=0D=0APoor=20thermal=20design=20or=20channel=20losses=20are=20generic= =20enough=20and=20can=20happen=20on=20any=20board.=0D=0A=0D=0A>=20Konrad=0D= =0A=0D=0A