From 7f1ea2ac30171d9a6aad2916a73e41fa68c8f137 Mon Sep 17 00:00:00 2001
From: Michel Thierry <michel.thierry@intel.com>
Date: Tue, 30 May 2017 17:05:46 -0700
Subject: [PATCH] drm/i915/guc: Fix doorbell id selection
Git-commit: 7f1ea2ac30171d9a6aad2916a73e41fa68c8f137
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900

We are passing parameters in the wrong order to find next zero bit, and
when it doesn't find anything it returns size (offset in the code), which
is always zero.

For reference the function is defined as:
find_next_bit( *addr, size, offset )

The incorrect parameter order was added by commit abddffdf3620e
("drm/i915/guc: Sanitize GuC client initialization"). Luckily, currently
we only use a single guc client and a single doorbell, which happens to be
zero; therefore it isn't necessary to backport this fix (which would be for
v4.12).

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170531000546.30762-1-michel.thierry@intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_guc_submission.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -105,7 +105,7 @@ static int __reserve_doorbell(struct i91
 		end += offset;
 	}
 
-	id = find_next_zero_bit(client->guc->doorbell_bitmap, offset, end);
+	id = find_next_zero_bit(client->guc->doorbell_bitmap, end, offset);
 	if (id == end)
 		return -ENOSPC;