diff options
| -rw-r--r-- | drivers/mtd/nand/raw/sunxi_nand.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c index 4fd1f8da6906..4282bc477761 100644 --- a/drivers/mtd/nand/raw/sunxi_nand.c +++ b/drivers/mtd/nand/raw/sunxi_nand.c @@ -1442,6 +1442,20 @@ static int sunxi_nfc_setup_data_interface(struct nand_chip *nand, int csline, if (timings->tRHW_min > (min_clk_period * 20)) min_clk_period = DIV_ROUND_UP(timings->tRHW_min, 20); + /* + * In non-EDO, tREA should be less than tRP to guarantee that the + * controller does not sample the IO lines too early. Unfortunately, + * the sunxi NAND controller does not allow us to have different + * values for tRP and tREH (tRP = tREH = tRW / 2). + * + * We have 2 options to overcome this limitation: + * + * 1/ Extend tRC to fulfil the tREA <= tRC / 2 constraint + * 2/ Use EDO mode (only works if timings->tRLOH > 0) + */ + if (timings->tREA_max > min_clk_period && !timings->tRLOH_min) + min_clk_period = timings->tREA_max; + tWB = sunxi_nand_lookup_timing(tWB_lut, timings->tWB_max, min_clk_period); if (tWB < 0) { @@ -1497,14 +1511,16 @@ static int sunxi_nfc_setup_data_interface(struct nand_chip *nand, int csline, return -EINVAL; } + sunxi_nand->timing_ctl = 0; + /* * 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. + * 30 ns. We should also use EDO mode if tREA is bigger than tRP. */ min_clk_period = NSEC_PER_SEC / real_clk_rate; - sunxi_nand->timing_ctl = ((min_clk_period * 2) < 30) ? - NFC_TIMING_CTL_EDO : 0; + if (min_clk_period * 2 < 30 || min_clk_period * 1000 < timings->tREA_max) + sunxi_nand->timing_ctl = NFC_TIMING_CTL_EDO; return 0; } |