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Niklas Cassel
33a6938e0c
The "DesignWare Cores PCI Express Controller Register Descriptions,
Version 4.60a", section "1.21.70 IATU_LWR_TARGET_ADDR_OFF_INBOUND_i",
fields LWR_TARGET_RW and LWR_TARGET_HW both state that:
"Field size depends on log2(BAR_MASK+1) in BAR match mode."
I.e. only the upper bits are writable, and the number of writable bits is
dependent on the configured BAR_MASK.
If we do not write the BAR_MASK before writing the iATU registers, we are
relying the reset value of the BAR_MASK being larger than the requested
BAR size (which is supplied in the struct pci_epf_bar which is passed to
pci_epc_set_bar()). The reset value of the BAR_MASK is SoC dependent.
Thus, if the struct pci_epf_bar requests a BAR size that is larger than the
reset value of the BAR_MASK, the iATU will try to write to read-only bits,
which will cause the iATU to end up redirecting to a physical address that
is different from the address that was intended.
Thus, we should always write the iATU registers after writing the BAR_MASK.
Fixes: f8aed6ec62 ("PCI: dwc: designware: Add EP mode support")
Link: https://lore.kernel.org/r/20241213143301.4158431-9-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: stable@vger.kernel.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.