From: Sascha Hauer <s.hauer@pengutronix.de>
To: Christian Hemp <c.hemp@phytec.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] mtd: nand_mxs: fix NAND error when change clk rate
Date: Mon, 9 Jan 2017 11:21:33 +0100 [thread overview]
Message-ID: <20170109102133.2hwmwjqeikbbh5ck@pengutronix.de> (raw)
In-Reply-To: <1482356321-19996-1-git-send-email-c.hemp@phytec.de>
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@phytec.de>
> ---
> drivers/mtd/nand/nand_mxs.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/mtd/nand/nand_mxs.c b/drivers/mtd/nand/nand_mxs.c
> index cba0bee..ce79bca 100644
> --- a/drivers/mtd/nand/nand_mxs.c
> +++ b/drivers/mtd/nand/nand_mxs.c
> @@ -2047,7 +2047,9 @@ static int mxs_nand_enable_edo_mode(struct mxs_nand_info *info)
> nand->select_chip(mtd, -1);
>
> /* [3] set the main IO clock, 100MHz for mode 5, 80MHz for mode 4. */
> + clk_disable(info->clk);
> clk_set_rate(info->clk, (mode == 5) ? 100000000 : 80000000);
> + clk_enable(info->clk);
Calling clk_disable doesn't guarantee that the clock is actually
disabled. If there's another user of the same clock then clk_disable
will only decrease the usage counter.
I think if possible we should fix this in the clock driver instead.
Sascha
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next prev parent reply other threads:[~2017-01-09 10:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-21 21:38 Christian Hemp
2016-12-21 22:29 ` Sam Ravnborg
2016-12-22 8:50 ` Christian Hemp
2016-12-22 17:55 ` Sam Ravnborg
2016-12-23 10:39 ` Sam Ravnborg
2016-12-27 17:07 ` Fabio Estevam
2017-01-09 10:21 ` Sascha Hauer [this message]
2017-08-21 16:26 ` Uwe Kleine-König
2017-08-21 16:31 ` Fabio Estevam
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