From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Wed, 29 Jan 2020 15:55:54 +0000 (+0900)
Subject: mtd: rawnand: denali_dt: insert udelay() after reset deassert
X-Git-Tag: v2020.04-rc2~22^2~5
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=21d4a3ca549b5b1b8243c845b15f91142bfa3528;p=oweals%2Fu-boot.git

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 91d0f20aae..1afc61f876 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -136,11 +136,19 @@ static int denali_dt_probe(struct udevice *dev)
 	}
 
 	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);
 }