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Wed, 12 Nov 2025 23:48:11 -0800 (PST) X-Google-Smtp-Source: AGHT+IF8rRkEuWW/6gSHvrkhgOhcnbTpcGFokK+8H6N4ylsRW3aMFxk3k4phtF2p1olCGtMTmr/Plw== X-Received: by 2002:a17:902:ebc6:b0:298:495c:1bf0 with SMTP id d9443c01a7336-2984edd2700mr69775255ad.44.1763020090661; Wed, 12 Nov 2025 23:48:10 -0800 (PST) Received: from [10.218.35.45] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c2bed5asm15548045ad.88.2025.11.12.23.48.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Nov 2025 23:48:10 -0800 (PST) Message-ID: <9dbae7ca-b24f-4591-99cf-7720ace6a452@oss.qualcomm.com> Date: Thu, 13 Nov 2025 13:18:04 +0530 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] schemas: pci: Document PCIe T_POWER_ON To: Manivannan Sadhasivam Cc: andersson@kernel.org, robh@kernel.org, krzk@kernel.org, helgaas@kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, lpieralisi@kernel.org, kw@linux.com, conor+dt@kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree-spec@vger.kernel.org, quic_vbadigan@quicinc.com References: <20251110112947.2071036-1-krishna.chundru@oss.qualcomm.com> Content-Language: en-US From: Krishna Chaitanya Chundru In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=E6/AZKdl c=1 sm=1 tr=0 ts=69158d3b cx=c_pps a=oF/VQ+ItUULfLr/lQ2/icg==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=5gsRW-pyyPTur7QFVg0A:9 a=QEXdDO2ut3YA:10 a=3WC7DwWrALyhR5TkjVHa:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTEzMDA1NCBTYWx0ZWRfX72N7qjXak4W0 dlK6Ye0p6CASENt09hpspehEWIbXR/bBfB/N7WLJLtxeqR9TWkdKpymkWNYEDhP1yH+txmabCvh 40YwZdpjQhH8KJxcPqvgBjLWMRjfERY4yg0wqbjeztRPRnHWym5Q5iTBr8YDH+FDXQdX0XiGUe5 flGdbtUeHKxIdgmZxZT9539YZ6MwPxAaLz7CA+lbPed+7t4SHoYF8zw2yaWvcT6Wp41cUDVC2KG uZHpN9u5dONT5PvQWrZvv1LCpDd1/FHgu0L9cCKe4ZXdKLqNUOA8Cz1r12l03QcEz0dusRwIw55 DqDZ/XAV2ADdB35pNe++3qY0EhIaHrFdf9wWvuB/FWFPqYBWfhZiBr80m7PGnqIFG+uUC+w4oga vCUh8RpMLfbMpRG6HkQTA7/wT43v3Q== X-Proofpoint-GUID: Bz-pIsrcUROCCq3cUakeneFkNTmztHbS X-Proofpoint-ORIG-GUID: Bz-pIsrcUROCCq3cUakeneFkNTmztHbS X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-12_06,2025-11-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 malwarescore=0 spamscore=0 clxscore=1015 phishscore=0 bulkscore=0 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2511130054 On 11/10/2025 5:33 PM, Manivannan Sadhasivam wrote: > On Mon, Nov 10, 2025 at 04:59:47PM +0530, Krishna Chaitanya Chundru wrote: >> From PCIe r6, sec 5.5.4 & Table 5-11 in sec 5.5.5 T_POWER_ON is the >> minimum amount of time(in us) that each component must wait in L1.2.Exit >> after sampling CLKREQ# asserted before actively driving the interface to >> ensure no device is ever actively driving into an unpowered component and >> these values are based on the components and AC coupling capacitors used >> in the connection linking the two components. >> >> This property should be used to indicate the T_POWER_ON for each Root Port. >> > I'm not sure if we should restrict this property to just Root Ports. Defining a > property in 'pci-bus-common.yaml' means, all PCI bridges could use it, but this > value is applicable to endpoint devices also. Better to add in pci-device.yaml then. > Also, you might want to add some info that the driver (or DT consumer) should > derive the T_POWER_ON Scale and T_POWER_ON Value from this value. ack - Krishna Chaitanya. > - Mani > >> Signed-off-by: Krishna Chaitanya Chundru >> --- >> Changes in v1: >> - Updated the commiit text (Mani). >> - Link to v1: https://lore.kernel.org/all/20251110112550.2070659-1-krishna.chundru@oss.qualcomm.com/#t >> >> dtschema/schemas/pci/pci-bus-common.yaml | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/dtschema/schemas/pci/pci-bus-common.yaml b/dtschema/schemas/pci/pci-bus-common.yaml >> index 5257339..bbe5510 100644 >> --- a/dtschema/schemas/pci/pci-bus-common.yaml >> +++ b/dtschema/schemas/pci/pci-bus-common.yaml >> @@ -152,6 +152,15 @@ properties: >> This property is invalid in host bridge nodes. >> maxItems: 1 >> >> + t-power-on-us: >> + description: >> + The minimum amount of time that each component must wait in >> + L1.2.Exit after sampling CLKREQ# asserted before actively driving >> + the interface to ensure no device is ever actively driving into an >> + unpowered component. This value is based on the components and AC >> + coupling capacitors used in the connection linking the two >> + components(PCIe r6.0, sec 5.5.4). >> + >> supports-clkreq: >> description: >> If present this property specifies that CLKREQ signal routing exists from >> -- >> 2.34.1 >> >>