Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 1 May 2023 17:25:02 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Paul Cercueil <paul@crapouillou.net>
Cc:     Lars-Peter Clausen <lars@metafoo.de>,
        Vinod Koul <vkoul@kernel.org>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        Nuno =?UTF-8?B?U8Oh?= <noname.nuno@gmail.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Christian =?UTF-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org,
        linux-iio@vger.kernel.org, linux-media@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH v3 03/11] iio: buffer-dma: Get rid of outgoing queue
Message-ID: <20230501172502.125e4859@jic23-huawei>
In-Reply-To: <1f63ffced9ed18309401af9a885310e1715b6538.camel@crapouillou.net>
References: <20230403154800.215924-1-paul@crapouillou.net>
        <20230403154800.215924-4-paul@crapouillou.net>
        <20230416152422.477ecf67@jic23-huawei>
        <1f63ffced9ed18309401af9a885310e1715b6538.camel@crapouillou.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Tue, 18 Apr 2023 10:08:21 +0200
Paul Cercueil <paul@crapouillou.net> wrote:

> Hi Jonathan,
>=20
> Le dimanche 16 avril 2023 =C3=A0 15:24 +0100, Jonathan Cameron a =C3=A9cr=
it=C2=A0:
> > On Mon,=C2=A0 3 Apr 2023 17:47:52 +0200
> > Paul Cercueil <paul@crapouillou.net> wrote:
> >  =20
> > > The buffer-dma code was using two queues, incoming and outgoing, to
> > > manage the state of the blocks in use.
> > >=20
> > > While this totally works, it adds some complexity to the code,
> > > especially since the code only manages 2 blocks. It is much easier
> > > to
> > > just check each block's state manually, and keep a counter for the
> > > next
> > > block to dequeue.
> > >=20
> > > Since the new DMABUF based API wouldn't use the outgoing queue
> > > anyway,
> > > getting rid of it now makes the upcoming changes simpler.
> > >=20
> > > With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and
> > > can
> > > be removed.
> > >=20
> > > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > >=20
> > > ---
> > > v2: - Only remove the outgoing queue, and keep the incoming queue,
> > > as we
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 want the buffer to start streaming dat=
a as soon as it is
> > > enabled.
> > > =C2=A0=C2=A0=C2=A0 - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now=
 functionally
> > > the
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 same as IIO_BLOCK_STATE_DONE. =20
> >=20
> > I'm not that familiar with this code, but with my understanding this
> > makes
> > sense.=C2=A0=C2=A0 I think it is independent of the earlier patches and=
 is a
> > useful
> > change in it's own right.=C2=A0 As such, does it make sense to pick this
> > up
> > ahead of the rest of the series? I'm assuming that discussion on the
> > rest will take a while.=C2=A0 No great rush as too late for the coming
> > merge
> > window anyway. =20
>=20
> Actually, you can pick patches 3 to 6 (when all have been acked). They
> add write support for buffer-dma implementations; which is a dependency
> for the rest of the patchset, but they can live on their own.

Remind me of that in the cover letter for v4.

Thanks,

Jonathan

>=20
> Cheers,
> -Paul