[PATCH 03/16] mtd: nand: sunxi: fix EDO mode selection

Boris Brezillon
2016-03-07T16:19:44Z

The ONFI spec says that EDO should be enabled if the host drives tRC less
than 30ns, but the code just tests for the tRC_min value extracted from
the timings exposed by the NAND chip not the timings actually configured
in the NAND controller.
Fix that by first rounding down the requested clk_rate with
clk_round_rate() and then checking if tRC is actually smaller than 30ns.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/mtd/nand/sunxi_nand.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index ab66d8d..a270720 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1101,6 +1101,7 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
struct sunxi_nfc *nfc = to_sunxi_nfc(chip->nand.controller);
u32 min_clk_period = 0;
s32 tWB, tADL, tWHR, tRHW, tCAD;
+ long real_clk_rate;

/* T1 <=> tCLS */
if (timings->tCLS_min > min_clk_period)
@@ -1198,17 +1199,20 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
/* TODO: A83 has some more bits for CDQSS, CS, CLHZ, CCS, WC */
chip->timing_cfg = NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD);

+ /* Convert min_clk_period from picoseconds to nanoseconds */
+ min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
+
+ chip->clk_rate = NSEC_PER_SEC / min_clk_period;
+ real_clk_rate = clk_round_rate(nfc->mod_clk, chip->clk_rate);
+
/*
* ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data
* output cycle timings shall be used if the host drives tRC less than
* 30 ns.
*/
- chip->timing_ctl = (timings->tRC_min < 30000) ? NFC_TIMING_CTL_EDO : 0;
-
- /* Convert min_clk_period from picoseconds to nanoseconds */
- min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
-
- chip->clk_rate = NSEC_PER_SEC / min_clk_period;
+ min_clk_period = NSEC_PER_SEC / real_clk_rate;
+ chip->timing_ctl = ((min_clk_period * 2) < 30) ?
+ NFC_TIMING_CTL_EDO : 0;

return 0;
}
--
2.1.4