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-rw-r--r--drivers/mtd/nand/atmel/nand-controller.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/mtd/nand/atmel/nand-controller.c b/drivers/mtd/nand/atmel/nand-controller.c
index 2c8baa0c2c4e..ceec21bd30c4 100644
--- a/drivers/mtd/nand/atmel/nand-controller.c
+++ b/drivers/mtd/nand/atmel/nand-controller.c
@@ -1364,7 +1364,18 @@ static int atmel_smc_nand_prepare_smcconf(struct atmel_nand *nand,
ret = atmel_smc_cs_conf_set_timing(smcconf,
ATMEL_HSMC_TIMINGS_TADL_SHIFT,
ncycles);
- if (ret)
+ /*
+ * Version 4 of the ONFI spec mandates that tADL be at least 400
+ * nanoseconds, but, depending on the master clock rate, 400 ns may not
+ * fit in the tADL field of the SMC reg. We need to relax the check and
+ * accept the -ERANGE return code.
+ *
+ * Note that previous versions of the ONFI spec had a lower tADL_min
+ * (100 or 200 ns). It's not clear why this timing constraint got
+ * increased but it seems most NANDs are fine with values lower than
+ * 400ns, so we should be safe.
+ */
+ if (ret && ret != -ERANGE)
return ret;
ncycles = DIV_ROUND_UP(conf->timings.sdr.tAR_min, mckperiodps);