[3.19.y-ckt stable] Patch "Revert "drm/i915: Declare the swizzling unknown for L-shaped configurations"" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Revert "drm/i915: Declare the swizzling unknown for L-shaped configurations"

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 43ec48ed66c098bc07cb4abfff9d7ef028e59f23 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter at ffwll.ch>
Date: Tue, 14 Jul 2015 12:29:27 +0200
Subject: Revert "drm/i915: Declare the swizzling unknown for L-shaped
 configurations"

commit d82c0ba6e306f079407f07003e53c262d683397b upstream.

This reverts commit 19ee835cdb0b5a8eb11a68f25a51b8039d564488.

It breaks existing old userspace which doesn't handle UNKNOWN
swizzling correct. Yes UNKNOWN was a thing back in 2009 and probably
still is on some other platforms, but it still pretty clearly broke
the testers machine. If we want this we need to extend the ioctl with
new paramters that only new userspace looks at.

Cc: Harald Arnesen <harald at skogtun.org>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Reported-by: Harald Arnesen <harald at skogtun.org>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/i915/i915_gem_tiling.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index 8ce8c5e..ffe9072 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -183,18 +183,8 @@ i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
 		if (IS_GEN4(dev)) {
 			uint32_t ddc2 = I915_READ(DCC2);

-			if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE)) {
-				/* Since the swizzling may vary within an
-				 * object, we have no idea what the swizzling
-				 * is for any page in particular. Thus we
-				 * cannot migrate tiled pages using the GPU,
-				 * nor can we tell userspace what the exact
-				 * swizzling is for any object.
-				 */
+			if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE))
 				dev_priv->quirks |= QUIRK_PIN_SWIZZLED_PAGES;
-				swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
-				swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
-			}
 		}

 		if (dcc == 0xffffffff) {
--
1.9.1