From: Emil Velikov Date: Fri, 4 Jun 2021 15:49:05 +0000 (+0100) Subject: drm/i915: apply WaEnableVGAAccessThroughIOPort as needed X-Git-Tag: howlett/maple/20220722_2~2440^2~24^2~59 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a3af0140663dc335e5c18277a61bb99bfcb60694;p=users%2Fjedix%2Flinux-maple.git drm/i915: apply WaEnableVGAAccessThroughIOPort as needed Currently as the workaround is applied the screen flickers. As a result we do not achieve seamless boot experience. Avoiding the issue in the common use-case might be hard, although we can resolve it for dual GPU setups - when the "other" GPU is primary and/or outputs are connected to it. With this I was able to get seamless experience on my Intel/Nvidia box, running systemd-boot and sddm/Xorg. Note that the i915 driver is within initrd while the Nvidia one is not. Without this patch, the splash presented by systemd-boot (UEFI BGRT) is torn down as the code-path kicks in, leaving the monitor blank until the login manager starts. Same issue were reported with plymouth/grub, although personally I wasn't able to get them to behave on my setup. Suggested-by: Ville Syrjälä Signed-off-by: Emil Velikov Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20210604154905.660142-1-emil.l.velikov@gmail.com --- diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c index f002b82ba9c0e..3385b45ecd4bb 100644 --- a/drivers/gpu/drm/i915/display/intel_vga.c +++ b/drivers/gpu/drm/i915/display/intel_vga.c @@ -29,6 +29,9 @@ void intel_vga_disable(struct drm_i915_private *dev_priv) i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv); u8 sr1; + if (intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE) + return; + /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */ vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); outb(SR01, VGA_SR_INDEX);