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[78.88.45.245]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-af91a21ac0asm938646466b.99.2025.08.05.10.06.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 10:06:32 -0700 (PDT) Message-ID: Date: Tue, 5 Aug 2025 19:06:29 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] arm64: dts: qcom: sa8155: Add gear and rate limit properties to UFS To: Manivannan Sadhasivam Cc: Krzysztof Kozlowski , Ram Kumar Dwivedi , alim.akhtar@samsung.com, avri.altman@wdc.com, bvanassche@acm.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, andersson@kernel.org, konradybcio@kernel.org, James.Bottomley@hansenpartnership.com, martin.petersen@oracle.com, agross@kernel.org, linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250722161103.3938-1-quic_rdwivedi@quicinc.com> <20250722161103.3938-3-quic_rdwivedi@quicinc.com> <2a3c8867-7745-4f0a-8618-0f0f1bea1d14@kernel.org> <1701ec08-21bc-45b8-90bc-1cd64401abd8@kernel.org> <2nm7xurqgzrnffustrsmswy2rbug6geadaho42qlb7tr2jirlr@uw5gaery445y> <11ea828a-6d35-4ac6-a207-0284870c28fc@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: eeDPOGog-Q82sTmBKceduCNdmaIFTlhf X-Proofpoint-GUID: eeDPOGog-Q82sTmBKceduCNdmaIFTlhf X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDExOSBTYWx0ZWRfXwodSLFSCoeKQ dGmH5FYv0SFJWcu4CylgpI8MlNE2NR649RosrSQSTxQsnzvCi/GRufTj0+Ahq9VNJp1BKyHBG5V flGIq5povmTkYs63GKsdQusaPmZfqjUItW7y67YrmevadmNyz1EPEcyV3KLBdU4N0yIUmRGbEJq pvR+R+Oqypqv8laOd/PQds4ypFdsLtMXlM/rtwMAPhjQ37k0s6AKiA56ROvRMMgNmS9xsVFcw6q mNwfvIhBe68l4d+rg08zPHj0YO+dVVY9NRMC7WonVwv2PzvyO59y3BuqwJPlYXRZHo5hyouews2 I13qr1QACIi8UA66lsfblvLGKEmhy/3D3uRc78xiSrmO5tIaVMyt9dgEpZLVydQvRb6NGKDAvZ7 AH/huzVOdwevJRmP2TjULMqcUj/ziP+PNRHWMsv8Bvn96BwrSmKV5czSahUUMh1s1zrz1iiD X-Authority-Analysis: v=2.4 cv=aJvwqa9m c=1 sm=1 tr=0 ts=68923a1a cx=c_pps a=JbAStetqSzwMeJznSMzCyw==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=Fgd5GahhPM9C-_jtZqkA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=uxP6HrT_eTzRwkO_Te1X:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-05_04,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 mlxscore=0 adultscore=0 priorityscore=1501 mlxlogscore=999 spamscore=0 impostorscore=0 clxscore=1015 bulkscore=0 phishscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508050119 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’s commit message, which is why I didn’t reply earlier. >>>>> >>>>> To clarify: the limitations are due to customer board designs, not our SoC. Some boards can't support higher gear operation, hence the need for optional limit-hs-gear and limit-rate properties. >>>>> >>>> >>>> That's vague and does not justify the property. You need to document >>>> instead hardware capabilities or characteristic. Or explain why they >>>> cannot. With such form I will object to your next patch. >>>> >>> >>> I had an offline chat with Ram and got clarified on what these properties are. >>> The problem here is not with the SoC, but with the board design. On some Qcom >>> customer designs, both the UFS controller in the SoC and the UFS device are >>> capable of operating at higher gears (say G5). But due to board constraints like >>> poor thermal dissipation, routing loss, the board cannot efficiently operate at >>> the higher speeds. >>> >>> So the customers wanted a way to limit the gear speed (say G3) and rate >>> (say Mode-A) on the specific board DTS. >> >> I'm not necessarily saying no, but have you explored sysfs for this? >> >> I suppose it may be too late (if the driver would e.g. init the UFS >> at max gear/rate at probe time, it could cause havoc as it tries to >> load the userland).. >> > > If the driver tries to run with unsupported max gear speed/mode, it will just > crash with the error spit. OK just a couple related nits that I won't bother splitting into separate emails rate (mode? I'm seeing both names) should probably have dt-bindings defines while gear doesn't have to since they're called G anyway, with the bindings description strongly discouraging use, unless absolutely necessary (e.g. in the situation we have right there) I'd also assume the code should be moved into the ufs-common code, rather than making it ufs-qcom specific Konrad