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author | Alexey Brodkin <Alexey.Brodkin@synopsys.com> | 2015-06-24 10:47:41 +0200 |
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committer | David S. Miller <davem@davemloft.net> | 2015-06-24 11:38:53 +0200 |
commit | f1590670ce069eefeb93916391a67643e6ad1630 (patch) | |
tree | fa6e866515a1a9997d78300baff581ce08cc2394 /net/core | |
parent | ip: report the original address of ICMP messages (diff) | |
download | linux-f1590670ce069eefeb93916391a67643e6ad1630.tar.xz linux-f1590670ce069eefeb93916391a67643e6ad1630.zip |
stmmac: troubleshoot unexpected bits in des0 & des1
Current implementation of descriptor init procedure only takes
care about setting/clearing ownership flag in "des0"/"des1"
fields while it is perfectly possible to get unexpected bits
set because of the following factors:
[1] On driver probe underlying memory allocated with
dma_alloc_coherent() might not be zeroed and so
it will be filled with garbage.
[2] During driver operation some bits could be set by SD/MMC
controller (for example error flags etc).
And unexpected and/or randomly set flags in "des0"/"des1"
fields may lead to unpredictable behavior of GMAC DMA block.
This change addresses both items above with:
[1] Use of dma_zalloc_coherent() instead of simple
dma_alloc_coherent() to make sure allocated memory is
zeroed. That shouldn't affect performance because
this allocation only happens once on driver probe.
[2] Do explicit zeroing of both "des0" and "des1" fields
of all buffer descriptors during initialization of
DMA transfer.
And while at it fixed identation of dma_free_coherent()
counterpart as well.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: arc-linux-dev@synopsys.com
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
0 files changed, 0 insertions, 0 deletions