mtd: rawnand: denali_dt: insert udelay() after reset deassert
When the reset signal is de-asserted, the HW-controlled bootstrap
starts running unless it is disabled in the SoC integration.
It issues some commands to detect a NAND chip, and sets up registers
automatically. Until this process finishes, software should avoid
any register access.
Without this delay function, some of UniPhier boards hangs up while
executing nand_scan_ident(). (denali_read_byte() is blocked)
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
index 91d0f20..1afc61f 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -136,11 +136,19 @@
}
ret = reset_get_bulk(dev, &resets);
- if (ret)
+ if (ret) {
dev_warn(dev, "Can't get reset: %d\n", ret);
- else
+ } else {
reset_deassert_bulk(&resets);
+ /*
+ * When the reset is deasserted, the initialization sequence is
+ * kicked (bootstrap process). The driver must wait until it is
+ * finished. Otherwise, it will result in unpredictable behavior.
+ */
+ udelay(200);
+ }
+
return denali_init(denali);
}