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Date: Thu, 28 Mar 2024 01:23:13 +0100
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Lizhi Hou <lizhi.hou@amd.com>
Cc: Louis Chauvet <louis.chauvet@bootlin.com>, Brian Xu <brian.xu@amd.com>,
 Raj Kumar Rampelli <raj.kumar.rampelli@amd.com>, Vinod Koul
 <vkoul@kernel.org>, Michal Simek <michal.simek@amd.com>, Jan Kuliga
 <jankul@alatek.krakow.pl>, <dmaengine@vger.kernel.org>,
 <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
 <stable@vger.kernel.org>
Subject: Re: [PATCH 2/3] dmaengine: xilinx: xdma: Fix synchronization issue
Message-ID: <20240328012257.4a5955f2@xps-13>
In-Reply-To: <b59dd8cd-fd75-5342-d411-817f33e0ff48@amd.com>
References: <20240327-digigram-xdma-fixes-v1-0-45f4a52c0283@bootlin.com>
	<20240327-digigram-xdma-fixes-v1-2-45f4a52c0283@bootlin.com>
	<b59dd8cd-fd75-5342-d411-817f33e0ff48@amd.com>
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X-GND-Sasl: miquel.raynal@bootlin.com

Hi Lizhi,

> > @@ -376,6 +378,8 @@ static int xdma_xfer_start(struct xdma_chan *xchan)
> >   		return ret; =20
> >   >   	xchan->busy =3D true; =20
> > +	xchan->stop_requested =3D false;
> > +	reinit_completion(&xchan->last_interrupt); =20
>=20
> If stop_requested is true, it should not start another transfer. So I wou=
ld suggest to add
>=20
>  =C2=A0=C2=A0=C2=A0=C2=A0 if (xchan->stop_requested)
>=20
>  =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=
=A0 return -ENODEV;

Maybe -EBUSY in this case?

I thought synchronize() was mandatory in-between. If that's not the
case then indeed we need to block or error-out if a new transfer
gets started.

>=20
> at the beginning of xdma_xfer_start().
>=20
> xdma_xfer_start() is protected by chan lock.
>=20
> >   >   	return 0; =20
> >   }

Thanks,
Miqu=C3=A8l