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Commit d8757433 authored by Victorien Vedrine's avatar Victorien Vedrine Committed by Stephen Boyd
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clk:mxs: Fix bug on frequency divider 



On drivers/clk/mxs/clk-frac.c, the function clk_frac_round_rate returned a bad
result. The division before multiplication computes a wrong value ; the
calculation is inverted to fix the problem. The second issue is that the exact
rate have decimals and they are truncate. The consequence is that the function
clk_frac_set_rate (which use the result of clk_frac_round_rate) computes a
wrong value for the register (the rate generated can be closer to the desired
rate). The correction is : if there is decimal to the result, it is rounded to
the next larger integer.
On drivers/clk/mxs/clk-frac.c, the function clk_frac_recalc_rate returned
a bad result. The multiplication is made before the division to compute a
correct value.

Signed-off-by: default avatarVictorien Vedrine <victorien.vedrine@ophrys.net>
Acked-by: default avatarShawn Guo <shawnguo@kernel.org>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent a1c22a4b

drivers/clk/mxs/clk-frac.c

+9 −3
Original line number Diff line number Diff line
@@ -41,11 +41,13 @@ static unsigned long clk_frac_recalc_rate(struct clk_hw *hw, 
{

	struct clk_frac *frac = to_clk_frac(hw);

	u32 div;

	u64 tmp_rate;



	div = readl_relaxed(frac->reg) >> frac->shift;

	div &= (1 << frac->width) - 1;



	return (parent_rate >> frac->width) * div;

	tmp_rate = (u64)parent_rate * div;

	return tmp_rate >> frac->width;

}



static long clk_frac_round_rate(struct clk_hw *hw, unsigned long rate,
@@ -54,7 +56,7 @@ static long clk_frac_round_rate(struct clk_hw *hw, unsigned long rate, 
	struct clk_frac *frac = to_clk_frac(hw);

	unsigned long parent_rate = *prate;

	u32 div;

	u64 tmp;

	u64 tmp, tmp_rate, result;



	if (rate > parent_rate)

		return -EINVAL;
@@ -67,7 +69,11 @@ static long clk_frac_round_rate(struct clk_hw *hw, unsigned long rate, 
	if (!div)

		return -EINVAL;



	return (parent_rate >> frac->width) * div;

	tmp_rate = (u64)parent_rate * div;

	result = tmp_rate >> frac->width;

	if ((result << frac->width) < tmp_rate)

		result += 1;

	return result;

}



static int clk_frac_set_rate(struct clk_hw *hw, unsigned long rate,