linux-kernel - [PATCH v2 1/6] drm/v3d: Document cache flushing ABI.

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Date:   Mon,  3 Dec 2018 14:24:33 -0800
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org,
        Dave Emett <david.emett@...adcom.com>,
        Thomas Spurden <thomas.spurden@...adcom.com>,
        Eric Anholt <eric@...olt.net>
Subject: [PATCH v2 1/6] drm/v3d: Document cache flushing ABI.

Right now, userspace doesn't do any L2T writes, but we should lay out
our expectations for how it works.

v2: Explicitly mention the VCD cache flushing requirements and that
    we'll flush the other caches before each of the CLs.

Signed-off-by: Eric Anholt <eric@...olt.net>
---
 include/uapi/drm/v3d_drm.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/uapi/drm/v3d_drm.h b/include/uapi/drm/v3d_drm.h
index 35c7d813c66e..ea70669d2138 100644
--- a/include/uapi/drm/v3d_drm.h
+++ b/include/uapi/drm/v3d_drm.h
@@ -52,6 +52,14 @@ extern "C" {
  *
  * This asks the kernel to have the GPU execute an optional binner
  * command list, and a render command list.
+ *
+ * The L1T, slice, L2C, L2T, and GCA caches will be flushed before
+ * each CL executes.  The VCD cache should be flushed (if necessary)
+ * by the submitted CLs.  The TLB writes are guaranteed to have been
+ * flushed by the time the render done IRQ happens, which is the
+ * trigger for out_sync.  Any dirtying of cachelines by the job (only
+ * possible using TMU writes) must be flushed by the caller using the
+ * CL's cache flush commands.
  */
 struct drm_v3d_submit_cl {
 	/* Pointer to the binner command list.
-- 
2.20.0.rc1