Messages in this thread Patch in this message | | | From | Fabio Estevam <> | Subject | [PATCH] clk: clk-divider: Fix infinite loop for table divider | Date | Tue, 6 May 2014 17:26:45 -0300 |
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From: Fabio Estevam <fabio.estevam@freescale.com>
Since commit e7489693b3 (clk: divider: Optimize clk_divider_bestdiv loop) we notice a system hang on mx6qboard.
The cause for the hang is well explained by Sascha Hauer [1]:
"This cannot work. _round_up_table is implemented like this:
static int _round_up_table(const struct clk_div_table *table, int div) { const struct clk_div_table *clkt; int up = _get_table_maxdiv(table);
for (clkt = table; clkt->div; clkt++) { if (clkt->div == div) return clkt->div; ... } ... }
Here when a table entry matches the input div this function will return exactly the input div. This means _next_div() will always return the same value and clk_divider_bestdiv() has an infinite loop:
for (i = 1; i <= maxdiv; i = _next_div(divider, i)) { ... } " [1] http://marc.info/?l=linux-arm-kernel&m=139940658726253&w=2
Remove the 'return _round_up_table' so that the system can work normally again.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> --- drivers/clk/clk-divider.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c index b3c8396..fc3e344 100644 --- a/drivers/clk/clk-divider.c +++ b/drivers/clk/clk-divider.c @@ -246,8 +246,6 @@ static int _next_div(struct clk_divider *divider, int div) if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) return __roundup_pow_of_two(div); - if (divider->table) - return _round_up_table(divider->table, div); return div; } -- 1.8.3.2
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