linux-kernel - [PATCH 2/3] mtd: nand: pxa3xx_nand: fix early spurious interrupt

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Message-Id: <1439323034-8820-2-git-send-email-robert.jarzmik@free.fr>
Date:	Tue, 11 Aug 2015 21:57:13 +0200
From:	Robert Jarzmik <robert.jarzmik@...e.fr>
To:	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Robert Jarzmik <robert.jarzmik@...e.fr>
Subject: [PATCH 2/3] mtd: nand: pxa3xx_nand: fix early spurious interrupt

When the nand is first probe, and upon the first command start, the
status bits should be cleared before the interrupts are unmasked.

The bug is tricky : if the bootloader left a status bit set, the
unmasking of interrupts does trigger the interrupt handler before the
first command is issued, blocking the good behavior of the nand.

The same would happen if in pxa3xx_nand code flow a status bit is left,
and then a command is started.

Signed-off-by: Robert Jarzmik <robert.jarzmik@...e.fr>
---
 drivers/mtd/nand/pxa3xx_nand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index ed44bddcc43f..edfe329cc9db 100644
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -451,8 +451,8 @@ static void pxa3xx_nand_start(struct pxa3xx_nand_info *info)
 	ndcr |= NDCR_ND_RUN;
 
 	/* clear status bits and run */
-	nand_writel(info, NDCR, 0);
 	nand_writel(info, NDSR, NDSR_MASK);
+	nand_writel(info, NDCR, 0);
 	nand_writel(info, NDCR, ndcr);
 }
 
-- 
2.1.4

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