The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 9472335eaa1452b51dc8e8edaa1a342997cb80c7 Mon Sep 17 00:00:00 2001
From: Herve Codina <herve.codina@xxxxxxxxxxx>
Date: Fri, 19 Nov 2021 16:03:16 +0100
Subject: [PATCH] mtd: rawnand: fsmc: Fix timing computation
Under certain circumstances, the timing settings calculated by
the FSMC NAND controller driver were inaccurate.
These settings led to incorrect data reads or fallback to
timing mode 0 depending on the NAND chip used.
The timing computation did not take into account the following
constraint given in SPEAr3xx reference manual:
twait >= tCEA - (tset * TCLK) + TOUTDEL + TINDEL
Enhance the timings calculation by taking into account this
additional constraint.
This change has no impact on slow timing modes such as mode 0.
Indeed, on mode 0, computed values are the same with and
without the patch.
NANDs which previously stayed in mode 0 because of fallback to
mode 0 can now work at higher speeds and NANDs which were not
working at all because of the corrupted data work at high
speeds without troubles.
Overall improvement on a Micron/MT29F1G08 (flash_speed tool):
mode0 mode3
eraseblock write speed 3220 KiB/s 4511 KiB/s
eraseblock read speed 4491 KiB/s 7529 KiB/s
Fixes: d9fb079571833 ("mtd: nand: fsmc: add support for SDR timings")
Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/20211119150316.43080-5-herve.codina@xxxxxxxxxxx
diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
index 0a6c9ef0ea8b..6b2bda815b88 100644
--- a/drivers/mtd/nand/raw/fsmc_nand.c
+++ b/drivers/mtd/nand/raw/fsmc_nand.c
@@ -94,6 +94,14 @@
#define FSMC_BUSY_WAIT_TIMEOUT (1 * HZ)
+/*
+ * According to SPEAr300 Reference Manual (RM0082)
+ * TOUDEL = 7ns (Output delay from the flip-flops to the board)
+ * TINDEL = 5ns (Input delay from the board to the flipflop)
+ */
+#define TOUTDEL 7000
+#define TINDEL 5000
+
struct fsmc_nand_timings {
u8 tclr;
u8 tar;
@@ -278,7 +286,7 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host,
{
unsigned long hclk = clk_get_rate(host->clk);
unsigned long hclkn = NSEC_PER_SEC / hclk;
- u32 thiz, thold, twait, tset;
+ u32 thiz, thold, twait, tset, twait_min;
if (sdrt->tRC_min < 30000)
return -EOPNOTSUPP;
@@ -310,13 +318,6 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host,
else if (tims->thold > FSMC_THOLD_MASK)
tims->thold = FSMC_THOLD_MASK;
- twait = max(sdrt->tRP_min, sdrt->tWP_min);
- tims->twait = DIV_ROUND_UP(twait / 1000, hclkn) - 1;
- if (tims->twait == 0)
- tims->twait = 1;
- else if (tims->twait > FSMC_TWAIT_MASK)
- tims->twait = FSMC_TWAIT_MASK;
-
tset = max(sdrt->tCS_min - sdrt->tWP_min,
sdrt->tCEA_max - sdrt->tREA_max);
tims->tset = DIV_ROUND_UP(tset / 1000, hclkn) - 1;
@@ -325,6 +326,21 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host,
else if (tims->tset > FSMC_TSET_MASK)
tims->tset = FSMC_TSET_MASK;
+ /*
+ * According to SPEAr300 Reference Manual (RM0082) which gives more
+ * information related to FSMSC timings than the SPEAr600 one (RM0305),
+ * twait >= tCEA - (tset * TCLK) + TOUTDEL + TINDEL
+ */
+ twait_min = sdrt->tCEA_max - ((tims->tset + 1) * hclkn * 1000)
+ + TOUTDEL + TINDEL;
+ twait = max3(sdrt->tRP_min, sdrt->tWP_min, twait_min);
+
+ tims->twait = DIV_ROUND_UP(twait / 1000, hclkn) - 1;
+ if (tims->twait == 0)
+ tims->twait = 1;
+ else if (tims->twait > FSMC_TWAIT_MASK)
+ tims->twait = FSMC_TWAIT_MASK;
+
return 0;
}
