--- /dev/null
+From cff5a08a72f64cc9fb3191a87903955fa0e2cf7f Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 13 Jan 2020 18:22:40 +0100
+Subject: efi/arm: Defer probe of PCIe backed efifb on DT systems
+
+From: Ard Biesheuvel <ardb@kernel.org>
+
+[ 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@google.com>
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Signed-off-by: Saravana Kannan <saravanak@google.com>
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Link: https://lore.kernel.org/r/20200113172245.27925-9-ardb@kernel.org
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ 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
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
