Re: [PATCH v1] drm/tegra: gem: Fix CPU-cache maintenance for BO's allocated using get_pages()

From: Dmitry Osipenko
Date: Wed Apr 03 2019 - 06:47:58 EST

07.03.2019 1:55, Dmitry Osipenko ÐÐÑÐÑ:
> 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@xxxxxxxxxxxxxxx>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>

Thierry, please don't forget about this patch.