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linux/include/uapi
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Chris Wilson f8c0c77b23 xdrm/i915: Use two 32bit reads for select 64bit REG_READ ioctls 
commit 648a9bc530 upstream.

Since the hardware sometimes mysteriously totally flummoxes the 64bit
read of a 64bit register when read using a single instruction, split the
read into two instructions. Since the read here is of automatically
incrementing timestamp counters, we also have to be very careful in
order to make sure that it does not increment between the two
instructions.

However, since userspace tried to workaround this issue and so enshrined
this ABI for a broken hardware read and in the process neglected that
the read only fails in some environments, we have to introduce a new
uABI flag for userspace to request the 2x32 bit accurate read of the
timestamp.

v2: Fix alignment check and include details of the workaround for
userspace.

Reported-by: Karol Herbst <freedesktop@karolherbst.de>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91317
Testcase: igt/gem_reg_read
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Tested-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
History 2015-08-11 09:57:37 +01:00
..
asm-generic asm-generic: Add renameat2 syscall 2014-05-20 10:59:38 +02:00
drm xdrm/i915: Use two 32bit reads for select 64bit REG_READ ioctls 2015-08-11 09:57:37 +01:00
linux USB: usbfs: allow URBs to be reaped after disconnection 2015-08-11 09:57:29 +01:00
mtd mtd: lpddr: add driver for LPDDR2-NVM PCM memories 2014-05-20 17:45:17 -07:00
rdma RDMA/uapi: Include socket.h in rdma_user_cm.h 2014-09-17 09:22:17 -07:00
scsi FCoE Updates for 3.9 2013-03-01 09:10:08 +00:00
sound ALSA: compress: fix the struct alignment to 4 bytes 2014-06-23 12:15:33 +02:00
video UAPI: (Scripted) Disintegrate include/video 2012-12-20 17:14:26 +00:00
xen xen: install xen/gntdev.h and xen/gntalloc.h 2014-02-11 10:12:36 -05:00
Kbuild UAPI: (Scripted) Set up UAPI Kbuild files 2012-10-02 18:01:35 +01:00