Messages in this thread | | | Date | Tue, 27 Jun 2023 19:48:14 +0900 | From | Krzysztof Wilczyński <> | Subject | Re: [PATCH V3] Revert "PCI: tegra194: Enable support for 256 Byte payload" |
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Hello,
> This reverts commit 4fb8e46c1bc4 ("PCI: tegra194: Enable > support for 256 Byte payload"). > > Consider a PCIe hierarchy with a PCIe switch and a device connected > downstream of the switch that has support for MPS which is the minimum in > the hierarchy, and root port programmed with an MPS in its DevCtl register > that is greater than the minimum. In this scenario, the default bus > configuration of the kernel i.e. "PCIE_BUS_DEFAULT" doesn't configure the > MPS settings in the hierarchy correctly resulting in the device with > support for minimum MPS in the hierarchy receiving the TLPs of size more > than that. Although this can be addressed by appending "pci=pcie_bus_safe" > to the kernel command line, it doesn't seem to be a good idea to always > have this commandline argument even for the basic functionality to work. > > Reverting commit 4fb8e46c1bc4 ("PCI: tegra194: Enable support for 256 > Byte payload") avoids this requirement and ensures that the basic > functionality of the devices irrespective of the hierarchy and the MPS of > the devices in the hierarchy. > > To reap the benefits of having support for higher MPS, optionally, one can > always append the kernel command line with "pci=pcie_bus_perf".
Applied to controller/tegra194, thank you!
[1/1] Revert "PCI: tegra194: Enable support for 256 Byte payload" https://git.kernel.org/pci/pci/c/606295f16360
Krzysztof
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