From 6f634d7efb8876e5953c30c0a613aaa5f575fe05 Mon Sep 17 00:00:00 2001 From: Jim Quinlan Date: Tue, 11 Oct 2022 14:42:07 -0400 Subject: [PATCH] PCI: brcmstb: Wait for 100ms following PERST# deassert commit 3ae140ad827b359bc4fa7c7985691c4c1e3ca8f4 upstream. 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. Link: https://lore.kernel.org/r/20221011184211.18128-3-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli --- drivers/pci/controller/pcie-brcmstb.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/drivers/pci/controller/pcie-brcmstb.c +++ b/drivers/pci/controller/pcie-brcmstb.c @@ -1038,8 +1038,15 @@ static int brcm_pcie_start_link(struct b 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);