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Subject: Re: [PATCH] mtd: rawnand: meson: Fix linking error on 32-bit
 platforms
To:     Nathan Chancellor <natechancellor@gmail.com>,
        Boris Brezillon <bbrezillon@kernel.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>
CC:     Richard Weinberger <richard@nod.at>,
        Kevin Hilman <khilman@baylibre.com>,
        <linux-mtd@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>, <linux-kernel@vger.kernel.org>
References: <20190129214657.5877-1-natechancellor@gmail.com>
From:   Liang Yang <liang.yang@amlogic.com>
Message-ID: <42d2e92e-9f5a-62b2-c0af-b7f3544d79d2@amlogic.com>
Date:   Wed, 30 Jan 2019 17:26:39 +0800
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Hi Nathan,

On 2019/1/30 5:46, Nathan Chancellor wrote:
> On arm little endian allyesconfig:
> 
>    ld.lld: error: undefined symbol: __aeabi_uldivmod
>    >>> referenced by meson_nand.c
>    >>> mtd/nand/raw/meson_nand.o:(meson_nfc_setup_data_interface) in archive drivers/built-in.a
> 
> The dividend tBERS_max is u64, meaning we need to use DIV_ROUND_UP_ULL
> (which wraps do_div) to prevent the compiler from emitting
> __aebi_uldivmod.
> 
> Fixes: 2d570b34b41a ("mtd: rawnand: meson: add support for Amlogic NAND flash controller")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>   drivers/mtd/nand/raw/meson_nand.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index e858d58d97b0..6f12a96195d1 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -1116,8 +1116,8 @@ int meson_nfc_setup_data_interface(struct nand_chip *nand, int csline,
>   				       div * NFC_CLK_CYCLE);
>   	meson_chip->tadl = DIV_ROUND_UP(PSEC_TO_NSEC(timings->tADL_min),
>   					div * NFC_CLK_CYCLE);
> -	tbers_clocks = DIV_ROUND_UP(PSEC_TO_NSEC(timings->tBERS_max),
> -				    div * NFC_CLK_CYCLE);
> +	tbers_clocks = DIV_ROUND_UP_ULL(PSEC_TO_NSEC(timings->tBERS_max),
> +					div * NFC_CLK_CYCLE);

Looks good to me:

Acked-by: Liang Yang <liang.yang@amlogic.com>

>   	meson_chip->tbers_max = ilog2(tbers_clocks);
>   	if (!is_power_of_2(tbers_clocks))
>   		meson_chip->tbers_max++;
>