Re: [PATCH 1/2] mtd: rawnand: fsmc: Reset NAND timings on resume()

[Boris Brezillon <bbrezillon@xxxxxxxxxx>]

On Fri, 18 Jan 2019 22:06:04 +0100
Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:

> When we go through a suspend/resume cycle the NAND
> timings may have been lost so reset the chip.

Actually, it's not only about resetting the timings (even if the side
effect of calling nand_reset() is that the core re-applies the
correct timings through ->setup_data_interface()). We need it to start
in a known working state.

> 
> This hardware will autonomously enable/disable the
> chip selects depending on what memory is accessed and
> chip selects are not software controlled, so we
> only lass chip select "0" for "all chips".

The FSMC driver only supports single CS chips which explain why you
only have to call nand_reset(chip, 0).

> 
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
>  drivers/mtd/nand/raw/fsmc_nand.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
> index c9149a37f8f0..4050843dd35e 100644
> --- a/drivers/mtd/nand/raw/fsmc_nand.c
> +++ b/drivers/mtd/nand/raw/fsmc_nand.c
> @@ -1164,6 +1164,7 @@ static int fsmc_nand_resume(struct device *dev)
>  		clk_prepare_enable(host->clk);
>  		if (host->dev_timings)
>  			fsmc_nand_setup(host, host->dev_timings);
> +		nand_reset(&host->nand, 0);
>  	}
>  
>  	return 0;


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