Messages in this thread Patch in this message |  | | From | Herve Codina <> | Subject | [PATCH 4/4] mtd: rawnand: fsmc: Fix timing computation | Date | Fri, 12 Nov 2021 15:38:55 +0100 |
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The timing setting were incorrect on some nands leading to a fallback to mode 0 timing on some Micron nand or to incorrect data reads on some Winbond NAND.
The timing computation did not take into account the following constraint given in SPEAr3xx reference manual: twait >= tCEA - tset*TCLK + TOUTDEL + TINDEL
This patch adds this constraint and fixes the issues on both nands having the both nands working at mode 3 timing. The change has no impact on slower timing mode such as mode 0. Indeed, on mode 0 timing, computed values are the same with and without the patch.
Signed-off-by: Herve Codina <herve.codina@bootlin.com> --- drivers/mtd/nand/raw/fsmc_nand.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c index bff09219ce3a..a3aa66f30869 100644 --- a/drivers/mtd/nand/raw/fsmc_nand.c +++ b/drivers/mtd/nand/raw/fsmc_nand.c @@ -278,7 +278,7 @@ 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, tmp; if (sdrt->tRC_min < 30000) return -EOPNOTSUPP; @@ -310,13 +310,6 @@ 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 +318,24 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host, else if (tims->tset > FSMC_TSET_MASK) tims->tset = FSMC_TSET_MASK; + twait = max(sdrt->tRP_min, sdrt->tWP_min); + + /* 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 + * With TOUTDEL = 7ns (Output delay from the flip-flops to the board) + * and TINDEL = 5ns (Input delay from the board to the flipflop) + */ + tmp = sdrt->tCEA_max - (tims->tset + 1)*hclkn*1000 + 7000 + 5000; + if (twait < tmp) + twait = tmp; + + 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; } -- 2.31.1
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