84 lines
3.0 KiB
Diff
84 lines
3.0 KiB
Diff
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From 218e958524c673d6e68737e7f82d80ba2b6ef59a Mon Sep 17 00:00:00 2001
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From: Javier Martinez Canillas <javierm@redhat.com>
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Date: Thu, 19 May 2022 14:40:07 +0200
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Subject: drivers/firmware: skip simpledrm if nvidia-drm.modeset=1 is set
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The Nvidia proprietary driver has some bugs that leads to issues if used
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with the simpledrm driver. The most noticeable is that does not register
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an emulated fbdev device.
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It just relies on a fbdev to be registered by another driver, that could
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be that could be attached to the framebuffer console. On UEFI machines,
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this is the efifb driver.
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This means that disabling the efifb driver will cause virtual consoles to
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not be present in the system when using the Nvidia driver. Legacy BIOS is
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not affected just because fbcon is not used there, but instead vgacon.
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Unless a VGA mode is specified using the vga= kernel command line option,
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in that case the vesafb driver is used instead and its fbdev attached to
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the fbcon.
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This is a problem because with CONFIG_SYSFB_SIMPLEFB=y, the sysfb platform
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code attempts to register a "simple-framebuffer" platform device (that is
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matched against simpledrm) and only registers either an "efi-framebuffer"
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or "vesa-framebuffer" if this fails to be registered due the video modes
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not being compatible.
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The Nvidia driver relying on another driver to register the fbdev is quite
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fragile, since it can't really assume those will stick around. For example
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there are patches posted to remove the EFI and VESA platform devices once
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a real DRM or fbdev driver probes.
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But in any case, moving to a simpledrm + emulated fbdev only breaks this
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assumption and causes users to not have VT if the Nvidia driver is used.
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So to prevent this, let's add a workaround and make the sysfb to skip the
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"simple-framebuffer" registration when nvidia-drm.modeset=1 option is set.
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This is quite horrible, but honestly I can't think of any other approach.
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For this to work, the CONFIG_FB_EFI and CONFIG_FB_VESA config options must
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be enabled besides CONFIG_DRM_SIMPLEDRM.
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Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
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Cherry-picked-for: https://bugs.archlinux.org/task/73720
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---
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drivers/firmware/sysfb.c | 18 +++++++++++++++++-
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1 file changed, 17 insertions(+), 1 deletion(-)
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--- a/drivers/firmware/sysfb.c
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+++ b/drivers/firmware/sysfb.c
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@@ -35,6 +35,22 @@
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#include <linux/screen_info.h>
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#include <linux/sysfb.h>
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+static int skip_simpledrm;
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+
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+static int __init simpledrm_disable(char *opt)
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+{
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+ if (!opt)
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+ return -EINVAL;
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+
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+ get_option(&opt, &skip_simpledrm);
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+
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+ if (skip_simpledrm)
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+ pr_info("The simpledrm driver will not be probed\n");
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+
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+ return 0;
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+}
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+early_param("nvidia-drm.modeset", simpledrm_disable);
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+
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static struct platform_device *pd;
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static DEFINE_MUTEX(disable_lock);
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static bool disabled;
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@@ -145,7 +161,7 @@ static __init int sysfb_init(void)
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/* try to create a simple-framebuffer device */
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compatible = sysfb_parse_mode(si, &mode);
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- if (compatible) {
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+ if (compatible && !skip_simpledrm) {
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pd = sysfb_create_simplefb(si, &mode, parent);
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if (!IS_ERR(pd))
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goto put_device;
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