On Tue, Jan 25, 2022 at 11:39 PM Bjorn Helgaas helgaas@kernel.org wrote:
[+cc Maarten, Maxime, Thomas; beginning of thread: https://lore.kernel.org/r/20220106000658.243509-1-helgaas@kernel.org]
On Tue, Jan 25, 2022 at 10:51:15AM +0800, Huacai Chen wrote:
Hi, Bjorn,
Why this series still missing in 5.17-rc1? :(
- It was posted late in the cycle (Jan 6, when the merge window
opened Jan 9), so it was too late to expect a significant change like this to be merged for v5.17. Right now is a good time to consider it again so it would some time in -next.
- As of now, this code is still in drivers/gpu, and I don't maintain
that area. It's up to the DRM folks, who are all cc'd here.
I would like to move this from drivers/gpu to drivers/pci, but that requires a little more work to resolve the initcall ordering problem with respect to vga_arb_device_init() and misc_init() [1].
Hmm, to me, keep it in drivers/gpu is just OK.
Huacai
Bjorn
[1] https://lore.kernel.org/linux-pci/CAAhV-H7FhAjM-Ha42Z1dLrE4PvC9frfyeU27KHWcy...
On Fri, Jan 7, 2022 at 12:21 AM Bjorn Helgaas helgaas@kernel.org wrote:
On Thu, Jan 06, 2022 at 02:44:42PM +0800, Huacai Chen wrote:
On Thu, Jan 6, 2022 at 8:07 AM Bjorn Helgaas helgaas@kernel.org wrote:
Previously we selected a device that owns the boot framebuffer as the default device in vga_arb_select_default_device(). This was only done in the vga_arb_device_init() subsys_initcall, so devices enumerated later, e.g., by pcibios_init(), were not eligible.
Fix this by moving the framebuffer device selection from vga_arb_select_default_device() to vga_arbiter_add_pci_device(), which is called after every PCI device is enumerated, either by the vga_arb_device_init() subsys_initcall or as an ADD_DEVICE notifier.
Note that if vga_arb_select_default_device() found a device owning the boot framebuffer, it unconditionally set it to be the default VGA device, and no subsequent device could replace it.
Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn Based-on-patch-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: Bruno Prémont bonbons@linux-vserver.org
drivers/gpu/vga/vgaarb.c | 37 +++++++++++++++++-------------------- 1 file changed, 17 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c index b0ae0f177c6f..aefa4f406f7d 100644 --- a/drivers/gpu/vga/vgaarb.c +++ b/drivers/gpu/vga/vgaarb.c @@ -72,6 +72,7 @@ struct vga_device { unsigned int io_norm_cnt; /* normal IO count */ unsigned int mem_norm_cnt; /* normal MEM count */ bool bridge_has_one_vga;
bool is_framebuffer; /* BAR covers firmware framebuffer */ unsigned int (*set_decode)(struct pci_dev *pdev, bool decode);};
@@ -565,10 +566,9 @@ void vga_put(struct pci_dev *pdev, unsigned int rsrc) } EXPORT_SYMBOL(vga_put);
-static void __init vga_select_framebuffer_device(struct pci_dev *pdev) +static bool vga_is_framebuffer_device(struct pci_dev *pdev) { #if defined(CONFIG_X86) || defined(CONFIG_IA64)
struct device *dev = &pdev->dev; u64 base = screen_info.lfb_base; u64 size = screen_info.lfb_size; u64 limit;@@ -583,15 +583,6 @@ static void __init vga_select_framebuffer_device(struct pci_dev *pdev)
limit = base + size;
/** Override vga_arbiter_add_pci_device()'s I/O based detection* as it may take the wrong device (e.g. on Apple system under* EFI).** Select the device owning the boot framebuffer if there is* one.*//* Does firmware framebuffer belong to us? */ for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) { flags = pci_resource_flags(pdev, i);@@ -608,13 +599,10 @@ static void __init vga_select_framebuffer_device(struct pci_dev *pdev) if (base < start || limit >= end) continue;
if (!vga_default_device())vgaarb_info(dev, "setting as boot device\n");else if (pdev != vga_default_device())vgaarb_info(dev, "overriding boot device\n");vga_set_default_device(pdev);
return true; }#endif
return false;}
static bool vga_arb_integrated_gpu(struct device *dev) @@ -635,6 +623,7 @@ static bool vga_arb_integrated_gpu(struct device *dev) static bool vga_is_boot_device(struct vga_device *vgadev) { struct vga_device *boot_vga = vgadev_find(vga_default_device());
struct pci_dev *pdev = vgadev->pdev; /* * We select the default VGA device in this order:@@ -645,6 +634,18 @@ static bool vga_is_boot_device(struct vga_device *vgadev) * Other device (see vga_arb_select_default_device()) */
/** We always prefer a firmware framebuffer, so if we've already* found one, there's no need to consider vgadev.*/if (boot_vga && boot_vga->is_framebuffer)return false;if (vga_is_framebuffer_device(pdev)) {vgadev->is_framebuffer = true;return true;}Maybe it is better to rename vga_is_framebuffer_device() to vga_is_firmware_device() and rename is_framebuffer to is_fw_framebuffer?
That's a great point, thanks!
The "framebuffer" term is way too generic. *All* VGA devices have a framebuffer, so it adds no information. This is really about finding the device that was used by firmware.
I renamed:
vga_is_framebuffer_device() -> vga_is_firmware_default() vga_device.is_framebuffer -> vga_device.is_firmware_default
I updated my local branch and pushed it to: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/v... with head 0f4caffa1297 ("vgaarb: Replace full MIT license text with SPDX identifier").
I don't maintain drivers/gpu/vga/vgaarb.c, so this branch is just for reference. It'll ultimately be up to the DRM folks to handle this.
I'll wait for any other comments or testing reports before reposting.
/* * A legacy VGA device has MEM and IO enabled and any bridges * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy@@ -1531,10 +1532,6 @@ static void __init vga_arb_select_default_device(void) struct pci_dev *pdev, *found = NULL; struct vga_device *vgadev;
list_for_each_entry(vgadev, &vga_list, list) {vga_select_framebuffer_device(vgadev->pdev);}if (!vga_default_device()) { list_for_each_entry_reverse(vgadev, &vga_list, list) { struct device *dev = &vgadev->pdev->dev;-- 2.25.1