linux-kernel - Re: [PATCH 5/5] drm/i915: Kick out vga console

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Message-ID: <20140630065955.GD7687@nuc-i3427.alporthouse.com>
Date:	Mon, 30 Jun 2014 07:59:55 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Ed Tomlinson <edt@....ca>
Cc:	Daniel Vetter <daniel.vetter@...ll.ch>,
	Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
	DRI Development <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Herrmann <dh.herrmann@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Dave Airlie <airlied@...ux.ie>
Subject: Re: [PATCH 5/5] drm/i915: Kick out vga console

On Sat, Jun 28, 2014 at 11:55:19PM -0400, Ed Tomlinson wrote:
> On Saturday 28 June 2014 15:28:22 Ed Tomlinson wrote:
> 
> Resend without html krud which causes list to bounce the message.
> 
> > Hi
> > 
> > This commit ( a4de05268e674e8ed31df6348269e22d6c6a1803 ) hangs my boot with 3.16-git.  Reverting it lets the boot proceed. 
> > 
> > I have an i7 with a built-in i915 and an pcie r7 260x.  The R7 is the primary console.  The i915 is initialized
> > but does not have a physical display attached.
> > 
> > With the patch applied the boot stops at the messages:
> > 
> > [drm] Memory usable by graphics device = 2048M
> > [drm] Replacing VGA console driver

The issue looks like that we are ripping out the radeon fb_con whilst it
is active and that upsets everyone. In which case, I think the
compromise is:


diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 5f44581..4915f1d 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1439,18 +1439,20 @@ static int i915_kick_out_vgacon(struct drm_i915_private *dev_priv)
 #else
 static int i915_kick_out_vgacon(struct drm_i915_private *dev_priv)
 {
-       int ret;
+       int ret = 0;
 
        DRM_INFO("Replacing VGA console driver\n");
 
        console_lock();
-       ret = do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES - 1, 1);
-       if (ret == 0) {
-               ret = do_unregister_con_driver(&vga_con);
-
-               /* Ignore "already unregistered". */
-               if (ret == -ENODEV)
-                       ret = 0;
+       if (con_is_bound(&vga_con)) {
+               ret = do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES - 1, 1);
+               if (ret == 0) {
+                       ret = do_unregister_con_driver(&vga_con);
+
+                       /* Ignore "already unregistered". */
+                       if (ret == -ENODEV)
+                               ret = 0;
+               }
        }
        console_unlock();

-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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