Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 8 Jun 2020 12:16:19 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Pavel Machek <pavel@denx.de>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        fengsheng <fengsheng5@huawei.com>,
        Xinwei Kong <kong.kongxinwei@hisilicon.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.19 15/28] spi: dw: use "smp_mb()" to avoid sending spi
 data error
Message-ID: <20200608111619.GB4593@sirena.org.uk>
References: <20200605140252.338635395@linuxfoundation.org>
 <20200605140253.279609547@linuxfoundation.org>
 <20200607200910.GA13138@amd>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="JYK4vJDZwFMowpUq"
Content-Disposition: inline
In-Reply-To: <20200607200910.GA13138@amd>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


--JYK4vJDZwFMowpUq
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Sun, Jun 07, 2020 at 10:09:11PM +0200, Pavel Machek wrote:

> > Because of out-of-order execution about some CPU architecture,
> > In this debug stage we find Completing spi interrupt enable ->
> > prodrucing TXEI interrupt -> running "interrupt_transfer" function
> > will prior to set "dw->rx and dws->rx_end" data, so this patch add
> > memory barrier to enable dw->rx and dw->rx_end to be visible and
> > solve to send SPI data error.

> So, this is apparently CPU-vs-device issue...

The commit message is a bit unclear but my read had been interrupt
handler racing with sending new data rather than an ordering issue with
writes to the hardware. =20

--JYK4vJDZwFMowpUq
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl7eHgIACgkQJNaLcl1U
h9DhCwf/d1dXgEHH5Hb83+eAVx5v90fL3DClK2WyN5AJ/z1D2CZILow8Ky35z2Yb
33tiaskGua1M+7vsabIQ9pYSZL8oOkYwrDwP5UXGTJK4pwJxkBEpFL5ab+x6dTc9
9TUx/93YOc/OhD45++q3dEzUmS8ZoPKHiwxaglfe76Dw6S2wSErBsACqmWWZMUvz
VkkLcuJDcxpL+jjIwWDfkD4jKovGgJd8g4dAoJ+WGBHGYSr0SqYxlBVWlYP0yPaV
+h8aMjgeKHdWytbm6DHuo3bBgxgGUoif0s9wbAYxaW0piJzB9DGqHBxFhMtE3FF3
PZZ49fhK8VXpyCy+4wNylwx+lE2JXg==
=cxCC
-----END PGP SIGNATURE-----

--JYK4vJDZwFMowpUq--