From 40a808f173008729a0c631ab84693b6a2b0dcfc9 Mon Sep 17 00:00:00 2001 From: Alexey Brodkin Date: Wed, 5 Apr 2017 17:50:09 +0300 Subject: [PATCH] ARCv2: SLC: Make sure busy bit is set properly on SLC flushing 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. Same fix made in Linux kernel: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c70c473396cbdec1168a6eff60e13029c0916854 Signed-off-by: Alexey Brodkin --- arch/arc/lib/cache.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/arc/lib/cache.c b/arch/arc/lib/cache.c index b6ec831..f1436bf 100644 --- a/arch/arc/lib/cache.c +++ b/arch/arc/lib/cache.c @@ -59,10 +59,16 @@ static unsigned int __before_slc_op(const int op) static void __after_slc_op(const int op, unsigned int reg) { - if (op & OP_FLUSH) /* flush / flush-n-inv both wait */ + if (op & OP_FLUSH) { /* flush / flush-n-inv both wait */ + /* + * Make sure "busy" bit reports correct status, + * see STAR 9001165532 + */ + read_aux_reg(ARC_AUX_SLC_CTRL); while (read_aux_reg(ARC_AUX_SLC_CTRL) & DC_CTRL_FLUSH_STATUS) ; + } /* Switch back to default Invalidate mode */ if (op == OP_INV)