From: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Fixes regression introduced by:
commit bf51d5e2cda5d36d98e4b46ac7fca9461e512c41
Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
Date: Wed Jul 3 17:12:13 2013 -0300
drm/i915: switch disable_power_well default value to 1
The bug I'm seeing can be reproduced with:
- Boot your Haswell machine
- Make sure the power well gets disabled, then enabled. You can check
this by seeing the messages print by hsw_set_power_well
- Stop your display manager
- echo 0 > /sys/class/vtconsole/vtcon1/bind
I can easily reproduce this by blacklising snd_hda_intel and booting
with eDP+HDMI.
If you do this and then look at dmesg, you'll see we're printing
infinite "Unclaimed register" messages. This is happening because
we're stuck on an infinite loop inside console_unlock(), which is
calling many functions from vgacon.c. And the code that's triggering
the error messages is from vgacon_set_cursor_size().
For some reason, what fixes the problem is the code that clears
VGA_MSR_MEM_EN from VGA_MSR_WRITE. If you add some debug messages,
you'll see that we're reading a value of 0 and writing 0 back to it. I
really don't know why this fixes the problem, but I am sure that if
you remove the code line that writes 0 back the bug won't stop. I
suspect this is probably some problem with how the hardware gets
reinitialized when we reenable the power well.
Also notice that function i915_disable_vga_mem already existed and was
removed on commit 6e1b4fdad5157bb9e88777d525704aba24389bee, I just
brought it back. Notice that the intel_drv.h declaration was still
there too.
I know some people will probably request to deeply investigate why
exactly vgacon is doing the wrong thing, and ask me to replace the
"for (;;)" that exists inside console_unlock() with something else,
but my goal here is to just fix the regression. I don't think it's
worth spending that much time on vgacon code. And this is our
regression anyway.
Notice that this is just a partial fix to fd.o #67813. This fixes the
case where the power well is already enabled when we unbind, not when
it's disabled when we unbind.
V2: - Rebase (first version was sent in September).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67813
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
drivers/gpu/drm/i915/intel_pm.c | 2 ++
2 files changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 45a87d1..bf22bea 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11064,6 +11064,18 @@ void i915_redisable_vga(struct drm_device *dev)
}
}
+void i915_disable_vga_mem(struct drm_device *dev)
+{
+ if (HAS_PCH_SPLIT(dev)) {
+ vga_get_uninterruptible(dev->pdev, VGA_RSRC_LEGACY_IO);
+ outb(inb(VGA_MSR_READ) & ~VGA_MSR_MEM_EN, VGA_MSR_WRITE);
+ vga_set_legacy_decoding(dev->pdev, VGA_RSRC_LEGACY_IO |
+ VGA_RSRC_NORMAL_IO |
+ VGA_RSRC_NORMAL_MEM);
+ vga_put(dev->pdev, VGA_RSRC_LEGACY_IO);
+ }
+}
+
static void intel_modeset_readout_hw_state(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e6d98fe..7ebe1bd 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5703,6 +5703,8 @@ static void hsw_set_power_well(struct drm_device *dev,
if (wait_for((I915_READ(HSW_PWR_WELL_DRIVER) &
HSW_PWR_WELL_STATE_ENABLED), 20))
DRM_ERROR("Timeout enabling power well\n");
+
+ i915_disable_vga_mem(dev);
}
if (IS_BROADWELL(dev)) {
--
1.8.3.1
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