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

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Message-ID: <CAApk1dXwAtoFRRq971fwsE+yrbJT1kcYnjzSwShHBrXkU+nv_g@mail.gmail.com>
Date:   Mon, 3 Dec 2018 17:22:54 +0000
From:   Dave Emett <david.emett@...adcom.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Thomas Spurden <thomas.spurden@...adcom.com>
Subject: Re: [PATCH 1/6] drm/v3d: Document cache flushing ABI.

> + * The caches (L1T, slice, and L2T) will be flushed before the job
> + * executes.  The TLB writes are guaranteed to have been flushed by

I would say before *each* job executes, as the caches are flushed
before both bin and render.
I wouldn't say "the caches" as not all of the V3D caches are flushed
before executing a control list. In particular, the VCD cache is not
cleared by the kernel driver (not even sure if there is a register
interface to do this); it is expected that the control list will do
this itself (using the CLEAR_VCD_CACHE instruction).
On 3.3 and earlier there is a separate L2C for instructions/uniforms
and a GCA. These do need to be flushed, and it looks like they are, so
they should be mentioned here.