From patchwork Wed Jan 29 15:55:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 240463 List-Id: U-Boot discussion From: yamada.masahiro at socionext.com (Masahiro Yamada) Date: Thu, 30 Jan 2020 00:55:54 +0900 Subject: [PATCH v2 1/4] mtd: rawnand: denali_dt: insert udelay() after reset deassert Message-ID: <20200129155557.32191-1-yamada.masahiro@socionext.com> 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 --- Changes in v2: None drivers/mtd/nand/raw/denali_dt.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) 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); }