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From 6f634d7efb8876e5953c30c0a613aaa5f575fe05 Mon Sep 17 00:00:00 2001
From: Jim Quinlan <jim2101024@gmail.com>
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 <jim2101024@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
---
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);
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