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[2.155.41.158]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b56e2ae73csm81216185e9.1.2026.11.05.09.40.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Nov 2026 09:40:47 -0800 (PST) From: =?UTF-8?q?Enrique=20Hern=C3=A1ndez=20Bello?= To: krzk@kernel.org Cc: shawn.lin@rock-chips.com, lpieralisi@kernel.org, kwilczynski@kernel.org, mani@kernel.org, bhelgaas@google.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, heiko@sntech.de, dlemoal@kernel.org, iav@iav.lv, devicetree@vger.kernel.org, linux-pci@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 1/2] dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay properties Date: Thu, 5 Nov 2026 17:40:42 +0000 Message-ID: <20261105174042.2307139-1-ehbello@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261105-exuberant-finch-of-domination-3fbd6c@quoll> References: <20261104215848.2087944-1-ehbello@gmail.com> <20261104215848.2087944-2-ehbello@gmail.com> <20261105-exuberant-finch-of-domination-3fbd6c@quoll> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261105_094051_501572_56E58C20 X-CRM114-Status: GOOD ( 15.28 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 05, 2026, Krzysztof Kozlowski wrote: > Vendor driver does not matter, it is antipattern. Do not mention it here > as reason to do such change. > > No need to repeat the diff. Understood, both go in the next version. > us or ms? ms. The 0 case is badly worded: the driver never holds PERST# for less than 100 us, whatever the value, and 0 just ends up at that floor. I will describe the floor instead of giving 0 a meaning of its own. > What is the nature of this timing? 100 ms is a lot. Are you sure you are > not describing RC delay (we have bindings for that already) The 100 ms is not something the board needs. It is the driver's current wait, T_PVPERL from the CEM spec, applied on every board. Because PERST# is already asserted when that wait starts, it is also the width of the reset pulse. On my board (ROCK Pi 4C) the slot supply is regulator-always-on, so power has been stable for seconds before probe and there is nothing left to settle. The problem goes the other way: the JMB585 behind it stops answering configuration reads when it is held in reset that long. A wait of 0 to 15 ms enumerated 17 times out of 17, 20 ms once out of 3, and 100 ms never in 5. So the board needs a shorter value, not a longer one. I do not know why this endpoint behaves this way. Which binding did you have in mind for the RC delay? If an existing one fits, I would rather use it. I also plan to drop rockchip,s2r-perst-inactive-ms, since it describes an OS power state rather than the hardware. Thanks, Enrique