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Thu, 06 Oct 2022 15:03:34 -0700 (PDT) From: Jim Quinlan To: linux-pci@vger.kernel.org, Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , Cyril Brulebois , bcm-kernel-feedback-list@broadcom.com, jim2101024@gmail.com, james.quinlan@broadcom.com Cc: Florian Fainelli , Lorenzo Pieralisi , Rob Herring , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , linux-rpi-kernel@lists.infradead.org (moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE), linux-arm-kernel@lists.infradead.org (moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v1 2/5] PCI: brcmstb: Wait for 100ms following PERST# deassert Date: Thu, 6 Oct 2022 18:03:18 -0400 Message-Id: <20221006220322.33000-3-jim2101024@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221006220322.33000-1-jim2101024@gmail.com> References: <20221006220322.33000-1-jim2101024@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221006_150337_570776_642B9F49 X-CRM114-Status: GOOD ( 11.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Be prudent and give some time for power and clocks to become stable. As described in the PCIe CEM specification sections 2.2 and 2.2.1; as well as PCIe r5.0, 6.6.1. Signed-off-by: Jim Quinlan --- drivers/pci/controller/pcie-brcmstb.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c index a45ce7d61847..39b545713ba0 100644 --- a/drivers/pci/controller/pcie-brcmstb.c +++ b/drivers/pci/controller/pcie-brcmstb.c @@ -1037,8 +1037,15 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie) pcie->perst_set(pcie, 0); /* - * Give the RC/EP time to wake up, before trying to configure RC. - * Intermittently check status for link-up, up to a total of 100ms. + * Wait for 100ms after PERST# deassertion; see PCIe CEM specification + * sections 2.2, PCIe r5.0, 6.6.1. + */ + msleep(100); + + /* + * Give the RC/EP even more time to wake up, before trying to + * configure RC. Intermittently check status for link-up, up to a + * total of 100ms. */ for (i = 0; i < 100 && !brcm_pcie_link_up(pcie); i += 5) msleep(5); -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel