[PATCH] mtd: nand: gpmi: reset BCH earlier, too, to avoid NAND startup problems

Wolfram Sang w.sang at pengutronix.de
Wed Dec 5 15:46:02 EST 2012

It could happen (1 out of 100 times) that NAND did not start up
correctly after warm rebooting, so the kernel could not find the UBI or
DMA timed out due to a stalled BCH. When resetting BCH together with
GPMI, the issue could not be observed anymore (after 10000+ reboots). We
probably need the consistent state already before sending any command to
NAND, even when no ECC is needed. I chose to keep the extra reset for
BCH when changing the flash layout to be on the safe side.

Signed-off-by: Wolfram Sang <w.sang at pengutronix.de>
Cc: Huang Shijie <b32955 at freescale.com>
Cc: Artem Bityutskiy <dedekind1 at gmail.com>
Cc: David Woodhouse <david.woodhouse at intel.com>

Would be really great to have in 3.7. Also a stable-candidate IMO.

 drivers/mtd/nand/gpmi-nand/gpmi-lib.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index 3502acc..84f0526 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -166,6 +166,15 @@ int gpmi_init(struct gpmi_nand_data *this)
 	if (ret)
 		goto err_out;
+	/*
+	 * Reset BCH here, too. We got failures otherwise :(
+	 * See later BCH reset for explanation of MX23 handling
+	 */
+	ret = gpmi_reset_block(r->bch_regs, GPMI_IS_MX23(this));
+	if (ret)
+		goto err_out;
 	/* Choose NAND mode. */
 	writel(BM_GPMI_CTRL1_GPMI_MODE, r->gpmi_regs + HW_GPMI_CTRL1_CLR);

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