linux-kernel - Re: [PATCH] mtd: rawnand: call onfi_fill_data_interface() once again after nand

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Message-ID: <20190207111606.6b72dc34@xps13>
Date:   Thu, 7 Feb 2019 11:16:06 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-mtd@...ts.infradead.org,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Brian Norris <computersforpeace@...il.com>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Boris Brezillon <bbrezillon@...nel.org>
Subject: Re: [PATCH] mtd: rawnand: call onfi_fill_data_interface() once
 again after nand_detect

Hi Masahiro,

Masahiro Yamada <yamada.masahiro@...ionext.com> wrote on Thu,  7 Feb
2019 18:57:56 +0900:

> nand_scan_ident() calls onfi_fill_data_interface() at its entry
> to set up the initial timing parameters.
> 
> The timing parameters are needed not only for ->setup_data_interface(),
> but also for giving the correct delay to NAND_OP_WAIT_RDY, for example.
> 
> If the driver sets the NAND_KEEP_TIMINGS flag, or does not support
> ->setup_data_interface() hook, those parameters will never updated. 

                                                            ^ be 

> 
> Before nand_detect(), we never know whether the chip is ONFi or not.
> So, onfi_fill_data_interface() has to assume the worst case, i.e.
> non-ONFi.

s/ONFi/ONFI/?

> 
> After nand_detect(), if the chip turns out to be ONFi-compliant,
> we can optimize tPROG_max, tBERS_max, etc.
> 
> Call onfi_fill_data_interface() once again.

Sorry but I don't get why this is needed as there is the same call at
the top of this function. Can you be more specific on where/when the
missing call produces a failure?

> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  drivers/mtd/nand/raw/nand_base.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 9b3d7ff..35e543c 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -5040,6 +5040,9 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips,
>  
>  	nand_deselect_target(chip);
>  
> +	/* If the chip turns out ONFi, we can optimize timing parameters. */
> +	onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0);
> +
>  	/* Check for a chip array */
>  	for (i = 1; i < maxchips; i++) {
>  		u8 id[2];


Thanks,
Miquèl