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Date:   Tue, 17 Aug 2021 19:56:30 +0200
From:   Pavel Machek <pavel@denx.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Ben Hutchings <ben.hutchings@mind.be>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 5.10 51/96] net: dsa: microchip: Fix ksz_read64()
Message-ID: <20210817175630.GB30136@amd>
References: <20210816125434.948010115@linuxfoundation.org>
 <20210816125436.659359567@linuxfoundation.org>
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Hi!

> [ Upstream commit c34f674c8875235725c3ef86147a627f165d23b4 ]
>=20
> ksz_read64() currently does some dubious byte-swapping on the two
> halves of a 64-bit register, and then only returns the high bits.
> Replace this with a straightforward expression.

The code indeed is very strange, but there are just 2 users, and they
will now receive byteswapped values, right? If it worked before, it
will be broken.

Did this get enough testing for -stable?

Is hw little endian or high endian or...? Note that ksz_write64()
still contains the strange code, at least in 5.10.

Best regards,
							Pavel
						=09
> +++ b/drivers/net/dsa/microchip/ksz_common.h
> @@ -210,12 +210,8 @@ static inline int ksz_read64(struct ksz_device *dev,=
 u32 reg, u64 *val)
>  	int ret;
> =20
>  	ret =3D regmap_bulk_read(dev->regmap[2], reg, value, 2);
> -	if (!ret) {
> -		/* Ick! ToDo: Add 64bit R/W to regmap on 32bit systems */
> -		value[0] =3D swab32(value[0]);
> -		value[1] =3D swab32(value[1]);
> -		*val =3D swab64((u64)*value);
> -	}
> +	if (!ret)
> +		*val =3D (u64)value[0] << 32 | value[1];
> =20
>  	return ret;
>  }

--=20
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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