[PATCH] mtd: nand_mxs: fix NAND error when change clk rate

[Sam Ravnborg]

On Wed, Dec 21, 2016 at 10:38:41PM +0100, Christian Hemp wrote:
> The function "nand_enable_edo_mode" changed the NAND clk rate, without turning
> it off. In this case it is posible to get the following errors:
>     MXS NAND: Error sending command
>     MXS NAND: Error sending command
>     MXS NAND: DMA read error
> 
> This can be fixed if the NAND clk is disabled before we change the clk
> rate.
> 
> Tested with:
> nand: NAND device: Manufacturer ID: 0x2c, Chip ID: 0xdc (Micron
> MT29F4G08ABADAWP), 512MiB, page size: 2048, OOB size: 64
> 
> Signed-off-by: Christian Hemp <c.hemp at phytec.de>
Tested-by: Sam Ravnborg <sam at ravnborg.org>

We had it running over night - not a single DMA error.
Tested with 16 different targets in an ON/OFF test.
I do not have numbers for the ON/OFF cycles but it is more than 10 each.
Previously we had a high frequency of these.
And tonight there was none.

Christian - if we ever meet in person I owe you a beer!

	Sam