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[78.88.45.245]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b8e9fcd8f17sm207101666b.12.2026.02.05.00.50.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Feb 2026 00:50:22 -0800 (PST) Message-ID: Date: Thu, 5 Feb 2026 09:50:20 +0100 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] of: property: Create devlink between PCI Host bridge and Root Port suppliers To: Manivannan Sadhasivam , robh@kernel.org, saravanak@kernel.org Cc: andersson@kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, qiang.yu@oss.qualcomm.com References: <20260205070640.10653-1-manivannan.sadhasivam@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260205070640.10653-1-manivannan.sadhasivam@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=DtpbOW/+ c=1 sm=1 tr=0 ts=698459d0 cx=c_pps a=qKBjSQ1v91RyAK45QCPf5w==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=HzLeVaNsDn8A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=yxBm9irkQl15ksekz78A:9 a=QEXdDO2ut3YA:10 a=NFOGd7dJGGMPyQGDc5-O:22 X-Proofpoint-GUID: lPZS0xXg2bWS1COi3GNx2G5b6PEJ_wg9 X-Proofpoint-ORIG-GUID: lPZS0xXg2bWS1COi3GNx2G5b6PEJ_wg9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjA1MDA2MyBTYWx0ZWRfX7DVv2s1bi48C DuUNxeNjzihcHZz/hqYu+2Ce0lTCJEeruPkBIUebOitldfNhrXWy4Uqr9tWHg6GtiJjpV3hs4Rh Z8MYPEVEX3ME1tH1y8N8qo0N/4tdYNUrSvNtHxq+5ZTrD5zhyO5gSp28wJbBrLSihz7zE7uwtEo b7bvudglzFCwNSar9TgA+QE9jJKk2SGMlVlYtMd/oqOXni6JQsDMxsimEpMfPF59agrsmpwOH2x jEP7WGN0bPRIm0VKP896naJCEFpEgyn1Nb+VdOiDoy/prFFdRdHm/On84bvS2r7epnwfN6O2Nwl +9SvW+KRPyZAJOeUYWPXJYKK00WrZYpucQ2h09weZQYd9IIepW4f+u+tWOZ2KM+DAKk3WklT8// QRWwsEo5K+zZVHxM8ktKLeujgkjAddaf2dqrHAa0AFdX2oMVVe5LsTk/rh4ULrS5/woI77wP1Cy 0vbkyKtriRqsMhBa2Kg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-05_01,2026-02-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 bulkscore=0 phishscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602050063 On 2/5/26 8:06 AM, Manivannan Sadhasivam wrote: > In the recent times, devicetree started to represent the PCI Host bridge > supplies like PHY in the Root Port nodes as seen in commit 38fcbfbd4207 > ("dt-bindings: PCI: qcom: Move PHY & reset GPIO to Root Port node"). But > the Host bridge drivers still need to control these supplies as a part of > their controller initialization/deinitialization sequence. > > So the Host bridge drivers end up parsing the Root Port supplies in their > probe() and controlled them. A downside to this approach is that the > devlink dependency between the suppliers and Host bridge is completely > broken. Due to this, the driver core probes the Host bridge drivers even if > the suppliers are not ready, causing probe deferrals and setup teardowns in > probe(). > > These probe deferrals sometime happen over 1000 times (as reported in Qcom > Glymur platform) leading to a waste of CPU resources and increase in boot > time. So to fix these unnecessary deferrals, create devlink between the > Host bridge and Root Port suppliers in of_fwnode_add_links(). This will > allow the driver core to probe the Host bridge drivers only when all Root > Port suppliers are available. > > Reported-by: Bjorn Andersson > Signed-off-by: Manivannan Sadhasivam > --- [...] This is not 'required' in bindings and device_type="pci" doesn't uniquely identify root complexes (as can be seen below).. but I suppose this is the best delimiter we've got Perhaps it could be made 'required'? Konrad > + for_each_available_child_of_node_scoped(con_np, child) { > + if (of_node_is_type(child, "pci")) { > + for_each_property_of_node(child, p) > + of_link_property(child, con_np, p->name); > + } > + } > + } > > return 0; > }