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mtd: nand: sunxi: fix clk rate calculation

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Unlike what is specified in the Allwinner datasheets, the NAND clock rate
is not equal to 2/T but 1/T. Fix the clock rate selection accordingly.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Boris Brezillon 2015-12-02 15:10:40 +01:00
parent 9edb47004e
commit 2f9992e080
1 changed files with 5 additions and 5 deletions
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10
drivers/mtd/nand/sunxi_nand.c
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@ -1208,12 +1208,12 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
/*
* Convert min_clk_period into a clk frequency, then get the
* appropriate rate for the NAND controller IP given this formula
* (specified in the datasheet):
* nand clk_rate = 2 * min_clk_rate
* Unlike what is stated in Allwinner datasheet, the clk_rate should
* be set to (1 / min_clk_period), and not (2 / min_clk_period).
* This new formula was verified with a scope and validated by
* Allwinner engineers.
*/
chip->clk_rate = (2 * NSEC_PER_SEC) / min_clk_period;
chip->clk_rate = NSEC_PER_SEC / min_clk_period;
return 0;
}