This requires a drm.debug=6 dmesg.

Jesse is the Batrail owner.

This bug is reported on BIOS v47. We do a further verification, rollback BIOS to v40 and find this bug can't duplicate on BIOS v40.

Try:

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index b5a3875..7475200 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -688,7 +688,7 @@ static void intel_crt_reset(struct drm_connector *connector)
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_attached_crt(connector);
 
-       if (HAS_PCH_SPLIT(dev)) {
+       if (HAS_PCH_SPLIT(dev) || IS_VALLEYVIEW(dev)) {
                u32 adpa;
 
                adpa = I915_READ(crt->adpa_reg);

(In reply to comment #4)
> Try:
> 
> diff --git a/drivers/gpu/drm/i915/intel_crt.c
> b/drivers/gpu/drm/i915/intel_crt.c
> index b5a3875..7475200 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -688,7 +688,7 @@ static void intel_crt_reset(struct drm_connector
> *connector)
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         struct intel_crt *crt = intel_attached_crt(connector);
>  
> -       if (HAS_PCH_SPLIT(dev)) {
> +       if (HAS_PCH_SPLIT(dev) || IS_VALLEYVIEW(dev)) {
>                 u32 adpa;
>  
>                 adpa = I915_READ(crt->adpa_reg);

Verify with this patch, VGA hotplug can work.

I think we might want to just use a gen >= 5 check for clarity. Luckily VGA is dying out, so we don't need to ponder forward compatibility issues.

(In reply to comment #6)
> I think we might want to just use a gen >= 5 check for clarity. Luckily VGA
> is dying out, so we don't need to ponder forward compatibility issues.

Poke.

Fixed with

commit 6190e2f8f69695117ead2010b2c411b5183396a1
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Aug 26 19:51:06 2013 -0300

    drm/i915: Apply the force-detect VGA w/a to Valleyview

Closing old verified.