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ARCv2: SLC: Make sure busy bit is set properly on SLC flushing

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As reported in STAR 9001165532, an SLC control reg read (for checking
busy state) right after SLC invalidate command may incorrectly return
NOT busy causing software to NOT spin-wait while operation is underway.
(and for some reason this only happens if L1 cache is also disabled - as
required by IOC programming model)

Suggested workaround is to do an additional Control Reg read, which
ensures the 2nd read gets the right status.

Cc: stable@vger.kernel.org  #4.10
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
[vgupta: reworte changelog a bit]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Alexey Brodkin 2017-03-29 17:15:11 +03:00 committed by Vineet Gupta
parent ae9955aeb8
commit c70c473396
1 changed files with 3 additions and 0 deletions
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3
arch/arc/mm/cache.c
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@ -633,6 +633,9 @@ noinline static void slc_entire_op(const int op)
write_aux_reg(ARC_REG_SLC_INVALIDATE, 1);
/* Make sure "busy" bit reports correct stataus, see STAR 9001165532 */
read_aux_reg(r);
/* Important to wait for flush to complete */
while (read_aux_reg(r) & SLC_CTRL_BUSY);
}