On Mon, Jul 11, 2022 at 10:11:00PM +0200, Lukas Wunner wrote: > On Thu, Jul 07, 2022 at 01:06:53PM -0600, Keith Busch wrote: > > On Thu, Jul 07, 2022 at 11:42:38AM -0400, Paul Luse wrote: > > > +config PCIE_TPH > > > + bool "PCI TPH (Transaction Layer Packet Processing Hints) capability support" > > > + help > > > + This enables PCI Express TPH (Transaction Layer Packet Processing Hints) by > > > + making sure they are saved and restored across resets. Enable this if your > > > + hardware uses the PCI Express TPH capabilities. For more information please > > > + refer to PCIe r6.0 sec 6.17. > > > > I'm not sure this needs a config option. Even if hardware isn't supporting TPH, > > this state save code doesn't takes up much space, and saving this config > > capability seems to always be the right thing if hardware is supporting TPH. > > We recently had a complaint from Christoph Hellwig that DOE support > should not "bloat every single kernel built with PCI support": > > https://lore.kernel.org/linux-pci/YkVBJ+nRA2g%2FWDxa@xxxxxxxxxxxxx/ > > And OpenWRT folks once tried to make PCI quirks conditional on a > config option to reduce kernel footprint by 12 kBytes on space- > constrained Mips routers: > > https://lore.kernel.org/linux-pci/1482306784-29224-1-git-send-email-john@xxxxxxxxxxx/ > > Paul has followed your advice and did away with the config option > in his most recent version of the patch, but I'm not sure that's > actually the right thing to do. I don't think TPH is a mainstream > PCIe feature and we need to cater to the needs of low-end devices > with PCIe as well. If the added code size from this is not negligable for any enviroment, then okay, fair enough. Paul, sorry for pointing you in the wrong direction.
