Chris Wilson cd078bf95d drm/i915/execlists: Use rmb() to order CSB reads ... We assume that the CSB is written using the normal ringbuffer coherency protocols, as outlined in kernel/events/ring_buffer.c: * (HW) (DRIVER) * * if (LOAD ->data_tail) { LOAD ->data_head * (A) smp_rmb() (C) * STORE $data LOAD $data * smp_wmb() (B) smp_mb() (D) * STORE ->data_head STORE ->data_tail * } So we assume that the HW fulfils its ordering requirements (B), and so we should use a complimentary rmb (C) to ensure that our read of its WRITE pointer is completed before we start accessing the data. The final mb (D) is implied by the uncached mmio we perform to inform the HW of our READ pointer. References: https://bugs.freedesktop.org/show_bug.cgi?id=105064 References: https://bugs.freedesktop.org/show_bug.cgi?id=105888 References: https://bugs.freedesktop.org/show_bug.cgi?id=106185 Fixes: 767a983ab2 ("drm/i915/execlists: Read the context-status HEAD from the HWSP") References: 61bf9719fa ("drm/i915/cnl: Use mmio access to context status buffer") Suggested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Michał Winiarski <michal.winiarski@intel.com> Cc: Rafael Antognolli <rafael.antognolli@intel.com> Cc: Michel Thierry <michel.thierry@intel.com> Cc: Timo Aaltonen <tjaalton@ubuntu.com> Tested-by: Timo Aaltonen <tjaalton@ubuntu.com> Acked-by: Michel Thierry <michel.thierry@intel.com> Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180511121147.31915-1-chris@chris-wilson.co.uk (cherry picked from commit 77dfedb5be) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>		2018-05-14 15:09:04 +03:00
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drm	drm/i915/execlists: Use rmb() to order CSB reads	2018-05-14 15:09:04 +03:00
host1x	gpu: host1x: Use IOMMU groups	2017-12-21 14:52:36 +01:00
ipu-v3	gpu: ipu-v3: prg: avoid possible array underflow	2018-03-15 17:52:08 +01:00
vga	vga_switcheroo: Let HDA autosuspend on mux change	2018-03-13 22:58:49 +01:00
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