On Fri, 18 Sep 2020 at 05:15, Sasha Levin <sashal@xxxxxxxxxx> wrote: > > From: Ard Biesheuvel <ardb@xxxxxxxxxx> > > [ Upstream commit 64c8a0cd0a535891d5905c3a1651150f0f141439 ] > > The new of_devlink support breaks PCIe probing on ARM platforms booting > via UEFI if the firmware exposes a EFI framebuffer that is backed by a > PCI device. The reason is that the probing order gets reversed, > resulting in a resource conflict on the framebuffer memory window when > the PCIe probes last, causing it to give up entirely. > > Given that we rely on PCI quirks to deal with EFI framebuffers that get > moved around in memory, we cannot simply drop the memory reservation, so > instead, let's use the device link infrastructure to register this > dependency, and force the probing to occur in the expected order. > > Co-developed-by: Saravana Kannan <saravanak@xxxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20200113172245.27925-9-ardb@xxxxxxxxxx > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> Same question as the previous time you proposed this patch for stable: is the of_devlink framework being backported in its entirety? If not, this patch does not belong in -stable. > --- > drivers/firmware/efi/arm-init.c | 107 ++++++++++++++++++++++++++++++-- > 1 file changed, 103 insertions(+), 4 deletions(-) > > diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c > index 8ee91777abce7..e4ddd6e6edb31 100644 > --- a/drivers/firmware/efi/arm-init.c > +++ b/drivers/firmware/efi/arm-init.c > @@ -14,10 +14,12 @@ > #define pr_fmt(fmt) "efi: " fmt > > #include <linux/efi.h> > +#include <linux/fwnode.h> > #include <linux/init.h> > #include <linux/memblock.h> > #include <linux/mm_types.h> > #include <linux/of.h> > +#include <linux/of_address.h> > #include <linux/of_fdt.h> > #include <linux/platform_device.h> > #include <linux/screen_info.h> > @@ -262,15 +264,112 @@ void __init efi_init(void) > efi_memmap_unmap(); > } > > +static bool efifb_overlaps_pci_range(const struct of_pci_range *range) > +{ > + u64 fb_base = screen_info.lfb_base; > + > + if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) > + fb_base |= (u64)(unsigned long)screen_info.ext_lfb_base << 32; > + > + return fb_base >= range->cpu_addr && > + fb_base < (range->cpu_addr + range->size); > +} > + > +static struct device_node *find_pci_overlap_node(void) > +{ > + struct device_node *np; > + > + for_each_node_by_type(np, "pci") { > + struct of_pci_range_parser parser; > + struct of_pci_range range; > + int err; > + > + err = of_pci_range_parser_init(&parser, np); > + if (err) { > + pr_warn("of_pci_range_parser_init() failed: %d\n", err); > + continue; > + } > + > + for_each_of_pci_range(&parser, &range) > + if (efifb_overlaps_pci_range(&range)) > + return np; > + } > + return NULL; > +} > + > +/* > + * If the efifb framebuffer is backed by a PCI graphics controller, we have > + * to ensure that this relation is expressed using a device link when > + * running in DT mode, or the probe order may be reversed, resulting in a > + * resource reservation conflict on the memory window that the efifb > + * framebuffer steals from the PCIe host bridge. > + */ > +static int efifb_add_links(const struct fwnode_handle *fwnode, > + struct device *dev) > +{ > + struct device_node *sup_np; > + struct device *sup_dev; > + > + sup_np = find_pci_overlap_node(); > + > + /* > + * If there's no PCI graphics controller backing the efifb, we are > + * done here. > + */ > + if (!sup_np) > + return 0; > + > + sup_dev = get_dev_from_fwnode(&sup_np->fwnode); > + of_node_put(sup_np); > + > + /* > + * Return -ENODEV if the PCI graphics controller device hasn't been > + * registered yet. This ensures that efifb isn't allowed to probe > + * and this function is retried again when new devices are > + * registered. > + */ > + if (!sup_dev) > + return -ENODEV; > + > + /* > + * If this fails, retrying this function at a later point won't > + * change anything. So, don't return an error after this. > + */ > + if (!device_link_add(dev, sup_dev, 0)) > + dev_warn(dev, "device_link_add() failed\n"); > + > + put_device(sup_dev); > + > + return 0; > +} > + > +static const struct fwnode_operations efifb_fwnode_ops = { > + .add_links = efifb_add_links, > +}; > + > +static struct fwnode_handle efifb_fwnode = { > + .ops = &efifb_fwnode_ops, > +}; > + > static int __init register_gop_device(void) > { > - void *pd; > + struct platform_device *pd; > + int err; > > if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI) > return 0; > > - pd = platform_device_register_data(NULL, "efi-framebuffer", 0, > - &screen_info, sizeof(screen_info)); > - return PTR_ERR_OR_ZERO(pd); > + pd = platform_device_alloc("efi-framebuffer", 0); > + if (!pd) > + return -ENOMEM; > + > + if (IS_ENABLED(CONFIG_PCI)) > + pd->dev.fwnode = &efifb_fwnode; > + > + err = platform_device_add_data(pd, &screen_info, sizeof(screen_info)); > + if (err) > + return err; > + > + return platform_device_add(pd); > } > subsys_initcall(register_gop_device); > -- > 2.25.1 >
