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[78.88.45.245]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-615a8f2d554sm8310553a12.27.2025.08.05.06.16.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 06:16:36 -0700 (PDT) Message-ID: <11ea828a-6d35-4ac6-a207-0284870c28fc@oss.qualcomm.com> Date: Tue, 5 Aug 2025 15:16:33 +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 , Krzysztof Kozlowski Cc: 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> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <2nm7xurqgzrnffustrsmswy2rbug6geadaho42qlb7tr2jirlr@uw5gaery445y> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=NN7V+16g c=1 sm=1 tr=0 ts=68920437 cx=c_pps a=qKBjSQ1v91RyAK45QCPf5w==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=n5nAzIlM4DwaeDdO57oA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=NFOGd7dJGGMPyQGDc5-O:22 X-Proofpoint-GUID: sK6Q7aQFFXD1UjJcjGYRgyIn6k1Zkr-M X-Proofpoint-ORIG-GUID: sK6Q7aQFFXD1UjJcjGYRgyIn6k1Zkr-M X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDA5NSBTYWx0ZWRfX5WPsoSVuU4EC ZpGGuNrjZb4p9EPDC9ujQ0Ji97RQHUodDie4s1TiO7M0n7dk+7PiDePDQfJfG8q/TUxn6OrTMyf Cxgjq7AbrRYrD2jn3GXMp41lVJeKk36xc2NixIIoLG74965Ye4Cc/JU4YsOCwsE/ZKjyYubyyh2 YjD+rpd3NqPuwsVVHB1RIi5Uj23OiE3u1h5iEub4utb468Krfb5SrhsvLDnDH3R+fXHIma504pQ KqCno2sL+zVcVURHlvBi2LNWqCuF9HmH7vG8ivdVmoMHPy7oCQMRPJkPmGSeV69bENIULmVGtrV WYlvcFmn5l1NJZjFNyJMbgumVMhZvlgP+CQDtwhxVrTqVprUdEDY+3bclj/GiWbBw+FViL+xru0 kMoUH7qMipjgZaxqKHDiDsSTd5lPF/YTHyfyFZNY52MIZbK4nJh3WqmJ5rxYIa95P50ERGtT 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_03,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 mlxscore=0 suspectscore=0 mlxlogscore=999 bulkscore=0 malwarescore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508050095 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).. Konrad