On Thu, Apr 17, 2025 at 05:48:04PM +0800, Hans Zhang wrote: > > > On 2025/4/17 16:39, Niklas Cassel wrote: > > On Thu, Apr 17, 2025 at 04:07:51PM +0800, Hans Zhang wrote: > > > On 2025/4/17 15:48, Niklas Cassel wrote: > > > > > > Hi Niklas and Shawn, > > > > > > Thank you very much for your discussion and reply. > > > > > > I tested it on RK3588 and our platform. By setting pci=pcie_bus_safe, the > > > maximum MPS will be automatically matched in the end. > > > > > > So is my patch no longer needed? For RK3588, does the customer have to > > > configure CONFIG_PCIE_BUS_SAFE or pci=pcie_bus_safe? > > > > > > Also, for pci-meson.c, can the meson_set_max_payload be deleted? > > > > I think the only reason why this works is because > > pcie_bus_configure_settings(), in the case of > > pcie_bus_config == PCIE_BUS_SAFE, will walk the bus and set MPS in > > the bridge to the lowest of the downstream devices: > > https://github.com/torvalds/linux/blob/v6.15-rc2/drivers/pci/probe.c#L2994-L2999 > > > > > > So Hans, if you look at lspci for the other RCs/bridges that don't > > have any downstream devices connected, do they also show DevCtl.MPS 256B > > or do they still show 128B ? > > > > Hi Niklas, > > It will show DevCtl.MPS 256B. Ok. I guess that just means that the bridge itself is included in pci_walk_bus(). Let's wait and see what people think about my proposal earlier in the thread, or if someone can think of something better. Kind regards, Niklas
