From: Thierry Reding <thierry.reding@gmail.com>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org,
Jonathan Hunter <jonathanh@nvidia.com>
Subject: Re: [PATCH v1] drm/tegra: gem: Fix CPU-cache maintenance for BO's allocated using get_pages()
Date: Thu, 18 Apr 2019 12:00:48 +0200 [thread overview]
Message-ID: <20190418100048.GE26909@ulmo> (raw)
In-Reply-To: <20190306225519.4538-1-digetx@gmail.com>
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On Thu, Mar 07, 2019 at 01:55:19AM +0300, Dmitry Osipenko wrote:
> The allocated pages need to be invalidated in CPU caches. On ARM32 the
> DMA_BIDIRECTIONAL flag only ensures that data is written-back to DRAM and
> the data stays in CPU cache lines. While the DMA_FROM_DEVICE flag ensures
> that the corresponding CPU cache lines are getting invalidated and nothing
> more, that's exactly what is needed for a newly allocated pages.
>
> This fixes randomly failing rendercheck tests on Tegra30 using the
> Opentegra driver for tests that use small-sized pixmaps (10x10 and less,
> i.e. 1-2 memory pages) because apparently CPU reads out stale data from
> caches and/or that data is getting evicted to DRAM at the time of HW job
> execution.
>
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/gpu/drm/tegra/gem.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Applied, thanks.
Thierry
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prev parent reply other threads:[~2019-04-18 10:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-06 22:55 [PATCH v1] drm/tegra: gem: Fix CPU-cache maintenance for BO's allocated using get_pages() Dmitry Osipenko
2019-04-03 10:47 ` Dmitry Osipenko
2019-04-18 10:00 ` Thierry Reding [this message]
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