linux-kernel - [PATCH v4 2/3] mtd: brcmnand: Force 8bit mode before doing nand_scan

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Message-ID: <1446185938-17520-3-git-send-email-anup.patel@broadcom.com>
Date:	Fri, 30 Oct 2015 11:48:57 +0530
From:	Anup Patel <anup.patel@...adcom.com>
To:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	Linux MTD <linux-mtd@...ts.infradead.org>
CC:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	"Mark Rutland" <mark.rutland@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	"Ian Campbell" <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	"Florian Fainelli" <f.fainelli@...il.com>,
	Pramod KUMAR <pramodku@...adcom.com>,
	Vikram Prakash <vikramp@...adcom.com>,
	Sandeep Tripathy <tripathy@...adcom.com>,
	Linux ARM Kernel <linux-arm-kernel@...ts.infradead.org>,
	Device Tree <devicetree@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
	Anup Patel <anup.patel@...adcom.com>
Subject: [PATCH v4 2/3] mtd: brcmnand: Force 8bit mode before doing nand_scan_ident()

Just like other NAND controllers, the NAND READID command only works
in 8bit mode for all versions of BRCMNAND controller.

This patch forces 8bit mode for each NAND CS in brcmnand_init_cs()
before doing nand_scan_ident() to ensure that BRCMNAND controller
is in 8bit mode when NAND READID command is issued.

Signed-off-by: Anup Patel <anup.patel@...adcom.com>
Reviewed-by: Ray Jui <rjui@...adcom.com>
Reviewed-by: Scott Branden <sbranden@...adcom.com>
---
 drivers/mtd/nand/brcmnand/brcmnand.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index dda96fa..641591d 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -1912,6 +1912,7 @@ static int brcmnand_init_cs(struct brcmnand_host *host)
 	struct mtd_info *mtd;
 	struct nand_chip *chip;
 	int ret;
+	u16 cfg_offs;
 	struct mtd_part_parser_data ppdata = { .of_node = dn };
 
 	ret = of_property_read_u32(dn, "reg", &host->cs);
@@ -1954,6 +1955,15 @@ static int brcmnand_init_cs(struct brcmnand_host *host)
 
 	chip->controller = &ctrl->controller;
 
+	/*
+	 * The bootloader might have configured 16bit mode but
+	 * NAND READID command only works in 8bit mode. We force
+	 * 8bit mode here to ensure that NAND READID commands works.
+	 */
+	cfg_offs = brcmnand_cs_offset(ctrl, host->cs, BRCMNAND_CS_CFG);
+	nand_writereg(ctrl, cfg_offs,
+		      nand_readreg(ctrl, cfg_offs) & CFG_BUS_WIDTH);
+
 	if (nand_scan_ident(mtd, 1, NULL))
 		return -ENXIO;
 
-- 
1.9.1

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