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;
From:   "Pandey, Radhey Shyam" <radhey.shyam.pandey@amd.com>
To:     Vinod Koul <vkoul@kernel.org>,
        Adrian Larumbe <adrianml@alumnos.upm.es>
CC:     Christoph Hellwig <hch@lst.de>,
        "michal.simek@xilinx.com" <michal.simek@xilinx.com>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH] dmaengine: remove DMA_MEMCPY_SG once again
Thread-Topic: [PATCH] dmaengine: remove DMA_MEMCPY_SG once again
Thread-Index: AQHYhmbE8Sz/pMmzUEa+n/KlIjKAjQ==
Date:   Wed, 22 Jun 2022 18:34:57 +0000
Message-ID: <DS7PR12MB595897FAB92B785B48BF2DFFB7B29@DS7PR12MB5958.namprd12.prod.outlook.com>
References: <20220606074733.622616-1-hch@lst.de> <Yp4/JW4P12s4siRz@matsya>
 <20220606195455.qmq3yu6mc6g4rmm2@sobremesa> <Yp7OFYFp7oyjyKx1@matsya>
In-Reply-To: <Yp7OFYFp7oyjyKx1@matsya>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?+h/aGlggxop1ZCmoR+wWAQf8YmdVmvWt4MKVqVCcedDwj/B/VdwOrimfoy42?=
 =?us-ascii?Q?310crN7cXFFEzD3fDLUD0oSHW72wXTPlvZE2re5/VewnPN2og4SrcdpYpTV+?=
 =?us-ascii?Q?72zBZLQth9o8YvEU1gqnIUkOOTEF17Vjo+rAhsm4aDHLZq1l/WKo4IEvrWd/?=
 =?us-ascii?Q?SVvm5Y+5j8C0HCAein1vQo5OtJmBaH0sSyQi1Lz7Aq+pqV1BwEd8tFOpD/ZO?=
 =?us-ascii?Q?LB/ymk7X6aPFu2mzU9YKJ0528P1F6+flojH/1mOCoQlcn08y7l+5Yoil9YOk?=
 =?us-ascii?Q?fhAe+hFoiLOviuiB4eACDDucvLklG1TDM4nyJBnQZvw6uOFQ/k05is8vUKaz?=
 =?us-ascii?Q?M+ky31lRuGZ81s8+dozS9Lb8ukGdvJVqXA1YVTRzG4fuFHiHUuGtAAse+VNE?=
 =?us-ascii?Q?1vjuFZDaiHnODKh89VJ+rRlb1l4NiJkv1IWU4BvxmdrGZ6L7EeAy8ozgmTCk?=
 =?us-ascii?Q?AcJef1MKiuctKWgf0LBEoHP3s1HlS0ZQu3XhMZsfl8wkwA2k79G/dnYOG3or?=
 =?us-ascii?Q?VDvrgvcgVsi6qkU7gNj3QvCQ/oicNOJP4V6XD4cVkaXUUyaXxDMGZTTcho2a?=
 =?us-ascii?Q?+hJoDsjM1dBaTWuHBmdXu8q9XNk8DnFEyMYES7W3hlO2gLBPy7mWdV2MoY1E?=
 =?us-ascii?Q?98xwAjC+bwtIF9RkEXmqwL1b1rRPfb1Mfr4zqy1I9YgpieqCsrjVI44IM23S?=
 =?us-ascii?Q?4kQ5G4ELItRrjar4/lGFwOZwzpIwYVxtGqkAtroNIxabCB95j23LJtmfPYXp?=
 =?us-ascii?Q?ePvM7NO4SEbWy9ikkx23t2y4jCU+ba8SHddtftbqRxwguQCYpPSxFiGZSkf1?=
 =?us-ascii?Q?SdEiG3PZS36hMfZpeXuPSboDgIlUJqnO+zJ5cDIUP1fir/arFqxar0rGwvFk?=
 =?us-ascii?Q?SwoV7dvoL+NJut0wlDNxFK9aOuR+4IJ6+BeCt7qPdeT7xxv5tTER8n9vnjtu?=
 =?us-ascii?Q?TuRxTVdVukvjzkgYIq4NmxRok1mldHHZU2lqPlsl5tOY0VLhZtA9kWkoup9/?=
 =?us-ascii?Q?mXQS/JUu7rKQ4Y5BUcou0Vn2hU+W15aKZJGtizZiuyX46qlEhJo2Jbtnlkop?=
 =?us-ascii?Q?C9cYp9iX0UDy4SB7gTd97bEIAlSfLL6JlV9jhBf4cN63JXLB1D46xZDwtyBH?=
 =?us-ascii?Q?unfEbx8TCwGZuwWGh3Lvm/TD0xGdFLYclSr6maP4rVULhhh9BjcCmVa9LkN1?=
 =?us-ascii?Q?8mc9wPLcZrVgTTNsP2d2hUUKZWxVkAH+n10MFZ+5dXGjLqLDuAoz7LMJBTEB?=
 =?us-ascii?Q?LHircFcVH2P0PQmSE/HNRPysmwsT/7qNx/ROdCUmoZEEpBiYEuOcnwv/1jpW?=
 =?us-ascii?Q?ctbRDWFvIGuxWkTijTvQtfp/S0GOur1cdy98RaHg4MVgUR3kcpZrHIuxSENM?=
 =?us-ascii?Q?1zfc/hPO3JHwkySt8Qb2m/XxKdV4EUJaOhF36gCWhQY18vMvY8i2Da3f6JRM?=
 =?us-ascii?Q?1PkFMIwzjGvZZdo8HYcW8adV7fSC2xq5wr1ISAGQGs9nasrrcy6I5nkNWxS/?=
 =?us-ascii?Q?pttj64raxZIvjzdk6IjSuTsPxUxZvM4RyNiD4oG92c1ZS25LH3pMQrWo+PWF?=
 =?us-ascii?Q?E14sBQHwOT6hrJXPI/c=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB5958.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 62a266b1-eb56-46f0-1aa3-08da547de846
X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Jun 2022 18:34:57.0431
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: Japmexo0WWNL0H32wmSqiGkdpctXUiH81pIMPi7TUhiLfoNfrhYVYpbDhqZLmxKs
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4288
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> -----Original Message-----
> From: Vinod Koul <vkoul@kernel.org>
> Sent: Tuesday, June 7, 2022 9:34 AM
> To: Adrian Larumbe <adrianml@alumnos.upm.es>
> Cc: Christoph Hellwig <hch@lst.de>; michal.simek@xilinx.com;
> dmaengine@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org
> Subject: Re: [PATCH] dmaengine: remove DMA_MEMCPY_SG once again
>=20
> On 06-06-22, 20:54, Adrian Larumbe wrote:
> > >On 06.06.2022 23:23, Vinod Koul wrote:
> > >On 06-06-22, 09:47, Christoph Hellwig wrote:
> > >> This was removed before due to the complete lack of users, but
> > >> 3218910fd585 ("dmaengine: Add core function and capability check
> > >> for
> > >> DMA_MEMCPY_SG") and 29cf37fa6dd9 ("dmaengine: Add consumer for
> the
> > >> new DMA_MEMCPY_SG API function.") added it back despite still not
> > >> having any users whatsoever.
> > >>
> > >> Fixes: 3218910fd585 ("dmaengine: Add core function and capability
> > >> check for DMA_MEMCPY_SG")
> > >> Fixes: 29cf37fa6dd9 ("dmaengine: Add consumer for the new
> > >> DMA_MEMCPY_SG API function.")
> > >
> > >This is consumer of the driver API and it was bought back with the
> > >premise that user will also come...
> >
> > It's commit 29cf37fa6dd9 ("dmaengine: Add consumer for the new
> > DMA_MEMCPY_SG API function.")
> >
> > The two previous commits add the new driver API callback and document i=
t.
> >
> > >Adrianm, Michal any reason why user is not mainline yet..?

The dma client are use case dependent and mostly on end-users=20
to upstream it. In the Xilinx tree, there is no CDMA  user apart from=20
dmatest and as of now, there is no plan to support any other client.

It should be fine to revert this support again.

> >
> > Just double checked the mainline, and all three commits are there.
>=20
> There are no clients in mainline which call this API. There is a driver w=
hich
> implements this API, but no users...
>=20
> $ git grep dmaengine_prep_dma_memcpy_sg
> include/linux/dmaengine.h:static inline struct dma_async_tx_descriptor
> *dmaengine_prep_dma_memcpy_sg(
>=20
> --
> ~Vinod