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

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Date:	Mon, 07 Jul 2014 06:45:49 -0400
From:	Ed Tomlinson <edt@....ca>
To:	Chris Wilson <chris@...is-wilson.co.uk>,
	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: [Intel-gfx] [PATCH 5/5] drm/i915: Kick out vga console

Daniel,

I am not quite sure I understand what you want me to test?
Do you want me to try it without:

> > +               if (ret == 0) {
> > +                       ret = do_unregister_con_driver(&vga_con);

Thanks
Ed


On Monday 07 July 2014 10:48:26 Daniel Vetter wrote:
> On Mon, Jun 30, 2014 at 07:59:55AM +0100, Chris Wilson wrote:
> > 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);
> 
> Hm, we should only conditionalize the take_over_console - unregistering
> vga_con is kinda the point to make sure it's gone for real. Ed, can you
> please retest with the if (con_is_bound) check just for the
> do_take_over_console call?
> 
> Still puzzled wtf is going on here since as David says this should be a
> no-op.
> 
> Thanks, Daniel
> > +
> > +                       /* Ignore "already unregistered". */
> > +                       if (ret == -ENODEV)
> > +                               ret = 0;
> > +               }
> >         }
> >         console_unlock();
> > 
> > -Chris
> > 
> 
> 

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