On Wed, May 02, 2018 at 01:48:27PM +0000, Gilles Buloz wrote: > Le 02/05/2018 15:26, Bjorn Helgaas a écrit : > > On Wed, May 02, 2018 at 12:57:31PM +0000, Gilles Buloz wrote: > >> Hi Bjorn, > >> See attached patch (tested ok this morning) > > This looks good. Minor comments below. > > > > I can fix minor things myself, but I do need a signed-off-by from you > > before applying (see > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst) > > > > Please add a changelog, too, and include the patch inline (as opposed > > to as an attachment) if possible. > > > >> --- include/linux/pci.h.orig 2018-03-26 16:51:18.050000000 +0000 > >> +++ include/linux/pci.h 2018-04-30 18:29:14.140000000 +0000 > >> @@ -193,6 +193,7 @@ > >> enum pci_bus_flags { > >> PCI_BUS_FLAGS_NO_MSI = (__force pci_bus_flags_t) 1, > >> PCI_BUS_FLAGS_NO_MMRBC = (__force pci_bus_flags_t) 2, > >> + PCI_BUS_FLAGS_NO_EXTCFG = (__force pci_bus_flags_t) 4, > > Best if you can rebase this to v4.17-rc1. > > > >> }; > >> > >> /* These values come from the PCI Express Spec */ > >> --- drivers/pci/probe.c.orig 2018-01-22 09:29:52.000000000 +0000 > >> +++ drivers/pci/probe.c 2018-05-02 13:44:35.530000000 +0000 > >> @@ -664,6 +664,23 @@ > >> } > >> } > >> > >> +static bool pci_bridge_child_bus_ext_cfg_accessible(struct pci_dev *bridge) > >> +{ > >> + int pos; > >> + u32 status; > >> + > >> + if (!pci_is_pcie(bridge) || /* PCI/PCI bridge */ > >> + (pci_pcie_type(bridge) == PCI_EXP_TYPE_PCIE_BRIDGE) || /* PCIe/PCI bridge in forward mode */ > >> + (pci_pcie_type(bridge) == PCI_EXP_TYPE_PCI_BRIDGE)) { /* PCIe/PCI bridge in reverse mode */ > >> + pos = pci_find_capability(bridge, PCI_CAP_ID_PCIX); > >> + if (pos) > >> + pci_read_config_dword(bridge, pos + PCI_X_STATUS, &status); > >> + return pos && (status & (PCI_X_STATUS_266MHZ | PCI_X_STATUS_533MHZ)); > >> + } > > Please arrange this so everything fits in 80 columns. > > > > If you can split it into several simpler "if" statements rather > > than one with a complicated expression, that would also be good. > > > >> + > >> + return true; > >> +} > >> + > >> static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent, > >> struct pci_dev *bridge, int busnr) > >> { > >> @@ -725,6 +742,19 @@ > >> /* Create legacy_io and legacy_mem files for this bus */ > >> pci_create_legacy_files(child); > >> > >> + /* > >> + * if bus_flags inherited from parent bus do not already report lack of extended config > >> + * space support, check if supported by child bus by checking its parent bridge > >> + */ > > Wrap to fit in 80 columns. > > > >> + if (bridge && !(child->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG)) { > > The double negative makes this a little bit hard to read. Maybe it > > could be improved by reversing the sense of something? > > > >> + if (!pci_bridge_child_bus_ext_cfg_accessible(bridge)) { > >> + child->bus_flags |= PCI_BUS_FLAGS_NO_EXTCFG; > >> + dev_info(&child->dev, "extended config space not accessible due to parent bridge\n"); > > In v4.17-rc1, there's a pci_info() that should work here (instead of > > dev_info()). > > > >> + } > >> + } else { > >> + dev_info(&child->dev, "extended config space not accessible due to parent bus\n"); > >> + } > >> + > >> return child; > >> } > >> > >> @@ -1084,6 +1114,9 @@ > >> u32 status; > >> u16 class; > >> > >> + if (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG) > >> + return PCI_CFG_SPACE_SIZE; > >> + > >> class = dev->class >> 8; > >> if (class == PCI_CLASS_BRIDGE_HOST) > >> return pci_cfg_space_size_ext(dev); > > . > > > OK I'm going to learn about signing (sorry this is my first > "official" patch). Great, welcome! The signoff is no big deal -- it's just plain text (no crypto signature or anything) and it's basically just an assertion that you wrote it and have the right to contribute it. > I'll download kernel v4.17-rc1 and write the patch for it; however I > hope I'll be able to test it on my platform without the freescale > addons I have on 4.1.35, because I don't want to send an untested > patch. Don't worry too much about the 4.1 vs 4.17 issue. If you tested it on 4.1.35 that should be fine. > For "if (bridge && !(child->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG))", > I don't understand what you mean with "double negative", as I only > have one "!" The "!" and the "NO" part of "NO_EXTCFG" is what I meant. E.g., maybe the flag could be something like "COMPAT_CFG_ONLY" so there's no negation in the test at all. > Do you think it's worth keeping the two dev_info() ? The code would > be smaller without; however this may help to have it for debug. > Maybe use _dbg instead of _info ? Probably one pci_info() is enough as a clue that extended config space isn't available below this point in the hierarchy. I personally don't like the _dbg() version because it's so complicated to figure out when the output is enabled. Bjorn
