drivers/gpu/drm/ast: Fix infinite loop if read fails

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[ Upstream commit 298360af3d ]

ast_get_dram_info() configures a window in order to access BMC memory.
A BMC register can be configured to disallow this, and if so, causes
an infinite loop in the ast driver which renders the system unusable.

Fix this by erroring out if an error is detected.  On powerpc systems with
EEH, this leads to the device being fenced and the system continuing to
operate.

Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161215051241.20815-1-ruscur@russell.cc
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

...

This commit is contained in:

Russell Currey 2016-12-15 16:12:41 +11:00 • committed by Sasha Levin

parent fcc5da2cf6

commit 1eb7f3ea46

1 changed files with 5 additions and 2 deletions

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drivers/gpu/drm/ast/ast_main.c

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