Bug 92451

> Hi,
> 
> I noticed that a HSW laptop gets a few new warnings since 4.2-rc
> kernels.  One error messages pops at each boot time:
> 
>  Console: switching to colour dummy device 80x25
>  [drm] Replacing VGA console driver
>  [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>  [drm] Driver supports precise vblank timestamp query.
>  vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem
>  [drm:drm_calc_timestamping_constants [drm]] *ERROR* crtc 21: Can't calculate constants, dotclock = 0!

There's patches for this one already, but I accidentally applied them for
-next, not -fixes. They should land for -rc6.

> Then a warning when I start powertop:
> 
>  WARNING: CPU: 1 PID: 1674 at drivers/gpu/drm/drm_atomic.c:889 drm_atomic_get_property+0x232/0x2b0 [drm]()
>  CPU: 1 PID: 1674 Comm: powertop Tainted: G        W       4.3.0-rc4-test+ #93
>  Hardware name: Hewlett-Packard HP ProBook 430 G1/1946, BIOS L73 Ver. 08.05 2013/03/15
>   ffffffffa005b289 ffff880059173ca8 ffffffff81346fa9 0000000000000000
>   ffff880059173ce0 ffffffff81063232 ffff8800372bc028 ffff8800373f3740
>   ffff8800372bc000 ffff880062ad37c0 0000000000000001 ffff880059173cf0
>  Call Trace:
>   [<ffffffff81346fa9>] dump_stack+0x4b/0x72
>   [<ffffffff81063232>] warn_slowpath_common+0x82/0xc0
>   [<ffffffff8106332a>] warn_slowpath_null+0x1a/0x20
>   [<ffffffffa0047a12>] drm_atomic_get_property+0x232/0x2b0 [drm]
>   [<ffffffffa00356dc>] drm_object_property_get_value+0x6c/0x70 [drm]
>   [<ffffffffa003330f>] dpms_show+0x2f/0x70 [drm]
>   [<ffffffff8145f090>] dev_attr_show+0x20/0x50
>   [<ffffffff8124b48c>] sysfs_kf_seq_show+0xbc/0x130
>   [<ffffffff81249d73>] kernfs_seq_show+0x23/0x30
>   [<ffffffff811f3d8a>] seq_read+0xca/0x360
>   [<ffffffff8124a7da>] kernfs_fop_read+0x10a/0x160
>   [<ffffffff811d0888>] __vfs_read+0x28/0xd0
>   [<ffffffff812cbe80>] ? security_file_permission+0xa0/0xc0
>   [<ffffffff811d102f>] ? rw_verify_area+0x4f/0xe0
>   [<ffffffff811d1143>] vfs_read+0x83/0x130
>   [<ffffffff811d1df6>] SyS_read+0x46/0xa0
>   [<ffffffff81001b40>] ? syscall_return_slowpath+0x50/0x130
>   [<ffffffff81659636>] entry_SYSCALL_64_fastpath+0x16/0x75
> 
> 
> Both don't look like serious issues, but not sexy to see at each time.