[Buildroot] [PATCH 0/3] libdrm: ARMv4/ARMv5 compatibility fixes

[Buildroot] [PATCH 0/3] libdrm: ARMv4/ARMv5 compatibility fixes

[Thomas Petazzoni]

Hello,

What prompted me to do this small patch series is this pending patch
from Bernd: http://patchwork.ozlabs.org/patch/559218/. It really
annoyed me to have to propagate this dependency that DRI support is
not available on ARMv4/ARMv5.

So I investigated, and found out that it was caused by one of our
patches on libdrm, which introduces ARMv6+ instructions. Since the CAS
stuff in libdrm is only an optimization, we can safely really on the
slow path for ARMv4/ARMv5. The CAS path is not an optimization for
Vivante GPUs for some reason, but since Vivante GPUs are only found in
ARMv6+ based SoCs anyway, we don't really care.

Fixing this patch allows:

 (1) To revert a former patch done on the X.org server to take into
     account this ARMv6+ dependency.

 (2) Discard Bernd's patch

 (3) Avoid future patches needed to propagate this ARMv6+ dependency.

Best regards,

Thomas

Thomas Petazzoni (3):
  libdrm: reformat patch 0001 with Git
  libdrm: adjust the ARM patch to work on ARMv4/ARMv5
  Revert "package/x11r7/xserver_xorg-server: dri needs arm >= v6"

 .../0001-Add-ARM-support-into-xf86drm.h.patch      | 56 ++++++++++++++++++++++
 package/libdrm/0001-update-arm.patch               | 37 --------------
 .../xserver_xorg-server/xserver_xorg-server.mk     |  3 +-
 3 files changed, 57 insertions(+), 39 deletions(-)
 create mode 100644 package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
 delete mode 100644 package/libdrm/0001-update-arm.patch

-- 
2.6.4

[Buildroot] [PATCH 1/3] libdrm: reformat patch 0001 with Git

[Thomas Petazzoni]

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 ...tch => 0001-Add-ARM-support-into-xf86drm.h.patch} | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)
 rename package/libdrm/{0001-update-arm.patch => 0001-Add-ARM-support-into-xf86drm.h.patch} (69%)

diff --git a/package/libdrm/0001-update-arm.patch b/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
similarity index 69%
rename from package/libdrm/0001-update-arm.patch
rename to package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
index 1a95a14..99a02a8 100644
--- a/package/libdrm/0001-update-arm.patch
+++ b/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
@@ -1,17 +1,24 @@
-[Adapted from yocto project]
+From c0950d73c8aa13f057707fb7933c65c147349376 Mon Sep 17 00:00:00 2001
+From: Lauren Post <lauren.post@freescale.com>
+Date: Tue, 22 Mar 2016 22:08:25 +0100
+Subject: [PATCH] Add ARM support into xf86drm.h
 
-Add ARM support into xf86drm.h.  This provides support for Xorg interface.
-Without this the vivante samples will hang during close requiring a reboot
+This provides support for Xorg interface.  Without this the vivante
+samples will hang during close requiring a reboot
 
+[Adapted from yocto project]
 Upstream-Status: Pending
-
 Signed-off-by: Lauren Post <lauren.post@freescale.com>
 Signed-off-by: Evan Kotara <evan.kotara@freescale.com>
+---
+ xf86drm.h | 17 +++++++++++++++++
+ 1 file changed, 17 insertions(+)
 
 diff --git a/xf86drm.h b/xf86drm.h
+index 481d882..1cc0075 100644
 --- a/xf86drm.h
 +++ b/xf86drm.h
-@@ -461,6 +461,23 @@ do {	register unsigned int __old __asm("
+@@ -469,6 +469,23 @@ do {	register unsigned int __old __asm("o0");		\
  		: "cr0", "memory");			\
  	} while (0)
  
@@ -35,3 +42,6 @@ diff --git a/xf86drm.h b/xf86drm.h
  #endif /* architecture */
  #endif /* __GNUC__ >= 2 */
  
+-- 
+2.6.4
+
-- 
2.6.4

[Buildroot] [PATCH 2/3] libdrm: adjust the ARM patch to work on ARMv4/ARMv5

[Thomas Petazzoni]

The ARM patch that was added in commit
94841d87fd2ff8ebf7af84d49e5095074958febf ("libdrm: fix support for
xserver with Vivante drivers") makes the assumption that ldrex/strex
is available on ARM. While this is true on ARMv6+, it is not true on
ARMv4/ARMv5. Due to this, we had to make follow-up commits like
7bac31ceea1b52986b1773a1bd4841110672f923
("package/x11r7/xserver_xorg-server: dri needs arm >= v6") and more is
needed in the reverse dependencies to disable DRI usage on
ARMv4/ARMv5.

In fact, it turns out that the CAS code in libdrm is only an
optimization, and it will gracefully fall back to a system call based
lock/unlock mechanism.

So we simply change the patch to only provide the optimized CAS
implementation on ARMv6+. The original reason for this patch was to
fix Vivante drivers, and Vivante GPUs are only used in ARMv6+ cores,
so we should be fine (famous last words).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 .../0001-Add-ARM-support-into-xf86drm.h.patch       | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch b/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
index 99a02a8..3c00e9c 100644
--- a/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
+++ b/package/libdrm/0001-Add-ARM-support-into-xf86drm.h.patch
@@ -1,4 +1,4 @@
-From c0950d73c8aa13f057707fb7933c65c147349376 Mon Sep 17 00:00:00 2001
+From 2e3dd0040e676530f7e735fab335ff449b9b3f4d Mon Sep 17 00:00:00 2001
 From: Lauren Post <lauren.post@freescale.com>
 Date: Tue, 22 Mar 2016 22:08:25 +0100
 Subject: [PATCH] Add ARM support into xf86drm.h
@@ -10,19 +10,28 @@ samples will hang during close requiring a reboot
 Upstream-Status: Pending
 Signed-off-by: Lauren Post <lauren.post@freescale.com>
 Signed-off-by: Evan Kotara <evan.kotara@freescale.com>
+[Thomas: change CAS code to only be used on ARMv6/ARMv7, and not
+ARMv4/ARMv5, which don't support ldrex/strex. If no CAS implementation
+is provided libdrm falls back to a system call for locking/unlocking.]
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
 ---
- xf86drm.h | 17 +++++++++++++++++
- 1 file changed, 17 insertions(+)
+ xf86drm.h | 22 ++++++++++++++++++++++
+ 1 file changed, 22 insertions(+)
 
 diff --git a/xf86drm.h b/xf86drm.h
-index 481d882..1cc0075 100644
+index 481d882..72341f6 100644
 --- a/xf86drm.h
 +++ b/xf86drm.h
-@@ -469,6 +469,23 @@ do {	register unsigned int __old __asm("o0");		\
+@@ -469,6 +469,28 @@ do {	register unsigned int __old __asm("o0");		\
  		: "cr0", "memory");			\
  	} while (0)
  
-+#elif defined(__arm__)
++# elif defined (__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
++	|| defined (__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) \
++	|| defined (__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) \
++	|| defined (__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) \
++	|| defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) \
++	|| defined(__ARM_ARCH_7EM__)
 +       #undef DRM_DEV_MODE
 +       #define DRM_DEV_MODE     (S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)
 +
-- 
2.6.4

[Buildroot] [PATCH 3/3] Revert "package/x11r7/xserver_xorg-server: dri needs arm >= v6"

[Thomas Petazzoni]

This reverts commit 7bac31ceea1b52986b1773a1bd4841110672f923.

This commit is no longer needed, since libdrm no longer needs arm >=
v6 support thanks to the fix to the CAS implementation.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 package/x11r7/xserver_xorg-server/xserver_xorg-server.mk | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/package/x11r7/xserver_xorg-server/xserver_xorg-server.mk b/package/x11r7/xserver_xorg-server/xserver_xorg-server.mk
index 3f6cda7..617bcbc 100644
--- a/package/x11r7/xserver_xorg-server/xserver_xorg-server.mk
+++ b/package/x11r7/xserver_xorg-server/xserver_xorg-server.mk
@@ -130,8 +130,7 @@ else # modular
 XSERVER_XORG_SERVER_CONF_OPTS += --disable-kdrive --disable-xfbdev
 endif
 
-# libdrm locking macros use armv6+ instructions on arm
-ifeq ($(BR2_PACKAGE_MESA3D_DRI_DRIVER)n$(BR2_ARM_CPU_ARMV4)$(BR2_ARM_CPU_ARMV5),yn)
+ifeq ($(BR2_PACKAGE_MESA3D_DRI_DRIVER),y)
 XSERVER_XORG_SERVER_CONF_OPTS += --enable-dri --enable-glx
 XSERVER_XORG_SERVER_DEPENDENCIES += mesa3d xproto_xf86driproto
 else
-- 
2.6.4

[Buildroot] [PATCH 0/3] libdrm: ARMv4/ARMv5 compatibility fixes

[Thomas Petazzoni]

Hello,

On Tue, 22 Mar 2016 22:28:58 +0100, Thomas Petazzoni wrote:

>   libdrm: reformat patch 0001 with Git
>   libdrm: adjust the ARM patch to work on ARMv4/ARMv5
>   Revert "package/x11r7/xserver_xorg-server: dri needs arm >= v6"

I've applied those three patches.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com