[PATCH 3.16.y-ckt 127/144] x86/reboot: Add ASRock Q1900DC-ITX mainboard reboot quirk

[Luis Henriques]

3.16.7-ckt10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Lippers-Hollmann <s.l-h@xxxxxx>

commit 80313b3078fcd2ca51970880d90757f05879a193 upstream.

The ASRock Q1900DC-ITX mainboard (Baytrail-D) hangs randomly in
both BIOS and UEFI mode while rebooting unless reboot=pci is
used. Add a quirk to reboot via the pci method.

The problem is very intermittent and hard to debug, it might succeed
rebooting just fine 40 times in a row - but fails half a dozen times
the next day. It seems to be slightly less common in BIOS CSM mode
than native UEFI (with the CSM disabled), but it does happen in either
mode. Since I've started testing this patch in late january, rebooting
has been 100% reliable.

Most of the time it already hangs during POST, but occasionally it
might even make it through the bootloader and the kernel might even
start booting, but then hangs before the mode switch. The same symptoms
occur with grub-efi, gummiboot and grub-pc, just as well as (at least)
kernel 3.16-3.19 and 4.0-rc6 (I haven't tried older kernels than 3.16).
Upgrading to the most current mainboard firmware of the ASRock
Q1900DC-ITX, version 1.20, does not improve the situation.

( Searching the web seems to suggest that other Bay Trail-D mainboards
  might be affected as well. )
--
Signed-off-by: Stefan Lippers-Hollmann <s.l-h@xxxxxx>
Cc: Matt Fleming <matt.fleming@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20150330224427.0fb58e42@mir
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 arch/x86/kernel/reboot.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 52b1157c53eb..f319bfea154e 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -181,6 +181,16 @@ static struct dmi_system_id __initdata reboot_dmi_table[] = {
 		},
 	},
 
+	/* ASRock */
+	{	/* Handle problems with rebooting on ASRock Q1900DC-ITX */
+		.callback = set_pci_reboot,
+		.ident = "ASRock Q1900DC-ITX",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
+			DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
+		},
+	},
+
 	/* ASUS */
 	{	/* Handle problems with rebooting on ASUS P4S800 */
 		.callback = set_bios_reboot,
--
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