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PCI: brcmstb: Wait for 100ms following PERST# deassert 

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>
This commit is contained in:
Jim Quinlan 2022-10-11 14:42:07 -04:00 committed by Lorenzo Pieralisi
parent 198acab177
commit 3ae140ad82
1 changed files with 9 additions and 2 deletions
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11
drivers/pci/controller/pcie-brcmstb.c
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@ -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);