PCI: dwc: Simplify unrolled iATU detection

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The unrolled version of the internal ATU has been available since the DWC
PCIe v4.80a IP core, but it may not be enabled.  Per [1], if unrolled ATU
is enabled, the PCIE_ATU_VIEWPORT does not exist and reads as 0xffffffff;
while if unrolled ATU is disabled, PCIE_ATU_VIEWPORT will contain some
zeros.

Simplify dw_pcie_iatu_unroll_enabled() by checking the value of
PCIE_ATU_VIEWPORT.

[1] DesignWare Cores, PCI Express Controller, Register Desciptions,
v.4.90a, December 2016, p.855

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20220624143428.8334-10-Sergey.Semin@baikalelectronics.ru
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>

...

This commit is contained in:

Serge Semin 2022-06-24 17:34:19 +03:00 • committed by Bjorn Helgaas

parent 6717331843

commit bbc7c4de33

1 changed files with 5 additions and 6 deletions

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drivers/pci/controller/dwc/pcie-designware.c

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