From: Vivek Das Mohapatra <vivek@xxxxxxxxxxxxx> This patch is to do with seamless handover, eg when the sequence is bootloader → plymouth → desktop. It switches the vga arbiter from the "other" GPU to the default one (intel in this case), so the driver can issue some io(). Signed-off-by: Vivek Das Mohapatra <vivek@xxxxxxxxxxxxx> Signed-off-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> --- Greetings all, This patch has been downstream for a while now yet it seems perfectly reasonable thing to have in the Linux kernel. https://github.com/ValveSoftware/steamos_kernel/commit/5431b5b1999c3d3b5efee817fb3373fbbd473063 drivers/gpu/drm/i915/display/intel_vga.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c index be333699c515..4f07b5ad5fa0 100644 --- a/drivers/gpu/drm/i915/display/intel_vga.c +++ b/drivers/gpu/drm/i915/display/intel_vga.c @@ -30,12 +30,14 @@ void intel_vga_disable(struct drm_i915_private *dev_priv) u8 sr1; /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */ - vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); - outb(SR01, VGA_SR_INDEX); - sr1 = inb(VGA_SR_DATA); - outb(sr1 | 1 << 5, VGA_SR_DATA); - vga_put(pdev, VGA_RSRC_LEGACY_IO); - udelay(300); + if (pdev == vga_default_device()) { + vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); + outb(SR01, VGA_SR_INDEX); + sr1 = inb(VGA_SR_DATA); + outb(sr1 | 1 << 5, VGA_SR_DATA); + vga_put(pdev, VGA_RSRC_LEGACY_IO); + udelay(300); + } intel_de_write(dev_priv, vga_reg, VGA_DISP_DISABLE); intel_de_posting_read(dev_priv, vga_reg); -- 2.27.0
