summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/nand
diff options
context:
space:
mode:
authorXiaolei Li <xiaolei.li@mediatek.com>2019-05-07 18:25:38 +0800
committerMiquel Raynal <miquel.raynal@bootlin.com>2019-06-27 20:05:24 +0200
commite1884ffddacc0424d7e785e6f8087bd12f7196db (patch)
treec0ca79e33910f71e203d9326aa73c03cf1dd2fb8 /drivers/mtd/nand
parent917cc5945f18fc9464d597b4c1bb50ac745d78b6 (diff)
downloadlinux-e1884ffddacc0424d7e785e6f8087bd12f7196db.tar.gz
linux-e1884ffddacc0424d7e785e6f8087bd12f7196db.tar.bz2
linux-e1884ffddacc0424d7e785e6f8087bd12f7196db.zip
mtd: rawnand: mtk: Correct low level time calculation of r/w cycle
At present, the flow of calculating AC timing of read/write cycle in SDR mode is that: At first, calculate high hold time which is valid for both read and write cycle using the max value between tREH_min and tWH_min. Secondly, calculate WE# pulse width using tWP_min. Thridly, calculate RE# pulse width using the bigger one between tREA_max and tRP_min. But NAND SPEC shows that Controller should also meet write/read cycle time. That is write cycle time should be more than tWC_min and read cycle should be more than tRC_min. Obviously, we do not achieve that now. This patch corrects the low level time calculation to meet minimum read/write cycle time required. After getting the high hold time, WE# low level time will be promised to meet tWP_min and tWC_min requirement, and RE# low level time will be promised to meet tREA_max, tRP_min and tRC_min requirement. Fixes: edfee3619c49 ("mtd: nand: mtk: add ->setup_data_interface() hook") Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Xiaolei Li <xiaolei.li@mediatek.com> Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Diffstat (limited to 'drivers/mtd/nand')
-rw-r--r--drivers/mtd/nand/raw/mtk_nand.c24
1 files changed, 21 insertions, 3 deletions
diff --git a/drivers/mtd/nand/raw/mtk_nand.c b/drivers/mtd/nand/raw/mtk_nand.c
index dceff28c9a31..23fe19397315 100644
--- a/drivers/mtd/nand/raw/mtk_nand.c
+++ b/drivers/mtd/nand/raw/mtk_nand.c
@@ -500,7 +500,8 @@ static int mtk_nfc_setup_data_interface(struct nand_chip *chip, int csline,
{
struct mtk_nfc *nfc = nand_get_controller_data(chip);
const struct nand_sdr_timings *timings;
- u32 rate, tpoecs, tprecs, tc2r, tw2r, twh, twst, trlt;
+ u32 rate, tpoecs, tprecs, tc2r, tw2r, twh, twst = 0, trlt = 0;
+ u32 thold;
timings = nand_get_sdr_timings(conf);
if (IS_ERR(timings))
@@ -536,11 +537,28 @@ static int mtk_nfc_setup_data_interface(struct nand_chip *chip, int csline,
twh = DIV_ROUND_UP(twh * rate, 1000000) - 1;
twh &= 0xf;
- twst = timings->tWP_min / 1000;
+ /* Calculate real WE#/RE# hold time in nanosecond */
+ thold = (twh + 1) * 1000000 / rate;
+ /* nanosecond to picosecond */
+ thold *= 1000;
+
+ /*
+ * WE# low level time should be expaned to meet WE# pulse time
+ * and WE# cycle time at the same time.
+ */
+ if (thold < timings->tWC_min)
+ twst = timings->tWC_min - thold;
+ twst = max(timings->tWP_min, twst) / 1000;
twst = DIV_ROUND_UP(twst * rate, 1000000) - 1;
twst &= 0xf;
- trlt = max(timings->tREA_max, timings->tRP_min) / 1000;
+ /*
+ * RE# low level time should be expaned to meet RE# pulse time,
+ * RE# access time and RE# cycle time at the same time.
+ */
+ if (thold < timings->tRC_min)
+ trlt = timings->tRC_min - thold;
+ trlt = max3(trlt, timings->tREA_max, timings->tRP_min) / 1000;
trlt = DIV_ROUND_UP(trlt * rate, 1000000) - 1;
trlt &= 0xf;