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clk: qcom: fix RCG M/N counter configuration

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Currently, a RCG's M/N counter (used for fraction division) is
set to either 'bypass' (counter disabled) or 'dual edge' (counter
enabled) based on whether the corresponding rcg struct has a mnd
field specified and a non-zero N.

In the case where M and N are the same value, the M/N counter is
still enabled by code even though no division takes place.
Leaving the RCG in such a state can result in improper behavior.
This was observed with the DSI pixel clock RCG when M and N were
both set to 1.

Add an additional check (M != N) to enable the M/N counter only
when it's needed for fraction division.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Fixes: bcd61c0f53 (clk: qcom: Add support for root clock
generators (RCGs))
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
This commit is contained in:
Archit Taneja 2015-03-04 15:19:35 +05:30 committed by Stephen Boyd
parent 0833b5ae69
commit 0b21503dbb
1 changed files with 1 additions and 1 deletions
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2
drivers/clk/qcom/clk-rcg2.c
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@ -243,7 +243,7 @@ static int clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
mask |= CFG_SRC_SEL_MASK | CFG_MODE_MASK;
cfg = f->pre_div << CFG_SRC_DIV_SHIFT;
cfg |= rcg->parent_map[f->src] << CFG_SRC_SEL_SHIFT;
if (rcg->mnd_width && f->n)
if (rcg->mnd_width && f->n && (f->m != f->n))
cfg |= CFG_MODE_DUAL_EDGE;
ret = regmap_update_bits(rcg->clkr.regmap,
rcg->cmd_rcgr + CFG_REG, mask, cfg);