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:   Akhil R <akhilrajeev@nvidia.com>
To:     Nathan Chancellor <nathan@kernel.org>
CC:     "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Krishna Yarlagadda <kyarlagadda@nvidia.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
        "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
        Rajesh Gumasta <rgumasta@nvidia.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "thierry.reding@gmail.com" <thierry.reding@gmail.com>,
        "vkoul@kernel.org" <vkoul@kernel.org>,
        Pavan Kunapuli <pkunapuli@nvidia.com>
Subject: RE: [PATCH v20 2/2] dmaengine: tegra: Add tegra gpcdma driver
Thread-Topic: [PATCH v20 2/2] dmaengine: tegra: Add tegra gpcdma driver
Thread-Index: AQHYJzmonI6OEQo+/E6QhQV6hFw0nqyfs/OAgADMAkCAAPwtAIAAnSDA
Date:   Thu, 24 Feb 2022 04:23:27 +0000
Message-ID: <DM5PR12MB1850C245826D8229E63141A0C03D9@DM5PR12MB1850.namprd12.prod.outlook.com>
References: <20220221153934.5226-1-akhilrajeev@nvidia.com>
 <20220221153934.5226-3-akhilrajeev@nvidia.com>
 <YhUBt20I471s9Bhv@dev-arch.archlinux-ax161>
 <DM5PR12MB1850EF14473F9F941FB12506C03C9@DM5PR12MB1850.namprd12.prod.outlook.com>
 <YhaAZNaav720xXXx@dev-arch.archlinux-ax161>
In-Reply-To: <YhaAZNaav720xXXx@dev-arch.archlinux-ax161>
Accept-Language: en-IN, en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?ID6J7D7DkyGdmz+UNL09rxT5zraOQLt15lkJUJk5+rjinIy022SVaCBP2rc5?=
 =?us-ascii?Q?wnrmJ7pIj+wo93qiJO5PqUaq4KncTGoImCIeugz/uEcIL6qAfNPQvX6uqJI7?=
 =?us-ascii?Q?WsO9XUUOgElOxrTHbFGCIqBd5Ge8D7e0bYcTn1Pg/B8xh9riL8i5Z8ctFozx?=
 =?us-ascii?Q?DtgCvVA/NwBLvs5SZlCKiAi0IeSVlDtMZzVDAxVwyskIuC1T0suskHaG7MdZ?=
 =?us-ascii?Q?wgPlz71hakJupUdvlnNq0OYSPSXXPGlsY/RrOdMUl459ftQiJopZUEPGNit1?=
 =?us-ascii?Q?08PYOc4BLsoVxjVQABrb5rMlEhTmI4crFjFMDKJKdqSLqsC5tLzg93Hb0a6L?=
 =?us-ascii?Q?YxrZx0q8nbL4cX9SFUR1Bxb5VGka8nI6donvlfQ/OGg4hUaRdku0kldQgUtH?=
 =?us-ascii?Q?KFbTJsLSAs3H7w7xCWz1p23qwBmlWG3DzI/rnJ4yHjH2bzfFUpMiVzHBY/oF?=
 =?us-ascii?Q?pADimPtHsDXI3JampSLjkBfSJ6z/dbwVRSF2QUrfGrD0dlqgVZVLqYg1Z5q9?=
 =?us-ascii?Q?zIquUxpnGv0yL79raohE0HkPukSj7bF2W5l8XfGUWhu4CUP7Weed8ZdJgUeC?=
 =?us-ascii?Q?QZk/S+dcRYzkC0ZbIrwfMNZCgCFVbDIl4IF3WhcPS2FqkzMifIAV3YE5Kw/b?=
 =?us-ascii?Q?eDWVApRpfQ0BlK+FinH65je/o8kaOmSaWK5M7nU3HU+LT0h1kFjFs4qL/h5e?=
 =?us-ascii?Q?OnFVz7H9O/qs0H8LZlO3z779COJOF3tp1MS8B3In7taNc05Ch6ZaMnRWHNjs?=
 =?us-ascii?Q?L5Ykgz32QgwvpUJxGuhljrFKAIM9cdHU9j/DSl8VkMZKQj9xzIWnT4GnSBo7?=
 =?us-ascii?Q?GFJ1Le/41kHNcQD+Ful2txb09YPkr2q5kX4CYxNk5r1kMllRTB5vqp6wr6Bm?=
 =?us-ascii?Q?PgVu7iJNujT7GfaGlVtrhS9yfnsPnynrdpf1K41ubWB0etHjBazSIAQyBD+C?=
 =?us-ascii?Q?kJLwhOTY69JAlIn/wJ1fjhepiENdazOvOGYQZ9wtTgz1Ang2QkV+y8wniS3N?=
 =?us-ascii?Q?hc30RRoMHbLQtm/dUCO2nKWSOoGJOBRH+o4mObpuORMLX+67q7fsok2fhfYq?=
 =?us-ascii?Q?05k90v0WtCgZ9jVfwljlcyW/QL+kYbOFZFhIpaLkbNg40vhtYN6UzELxPTuq?=
 =?us-ascii?Q?FbuugWx2Iao4Yy8bmIJ1GNmzfBI8GG+D+Rt08W0iijmi5F5AtDdj9uymckDB?=
 =?us-ascii?Q?kWK87EKxnitT0xFB08qhYBu9RP4OfQ+eicdNHiZxahrs5SxRuuKN7UxOaTBl?=
 =?us-ascii?Q?gB+yKJAiny039LMefABaK5uStBaRuH9L8JfX0txVJC6GvG+EJm6eTNCVYYr2?=
 =?us-ascii?Q?24Qb528U4Ife+7LmnQP2SzPjQuEav04v6DwRuGeMVEFAzQRAVdsURX++ZoW7?=
 =?us-ascii?Q?FBIE9V+eicVkxghQZ9pw3KAegBanC+kQY0h+wmY6F9NoXqarbR8kUlglnvLc?=
 =?us-ascii?Q?11RrXubZBHuI8bfS4Fzz5PKrNoCO1zLYfZJYWbyhvWf69ss1W3MdYRY8sVrr?=
 =?us-ascii?Q?bUGnQK6xwoAVXC7wxnMNig/rE/QlV/2hdNE/3aQw5CyPeCOodnUDTr7yBw+I?=
 =?us-ascii?Q?TRWOYpPt/5veOzE6GiPec0dVQs2TvW6qwneLbLEv4MU0hF/acbXRL7pIImxN?=
 =?us-ascii?Q?eU2xEt8D81j14tLZa7MdBiU=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: DM5PR12MB1850.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 3f3d898d-44c5-4340-30b8-08d9f74d6816
X-MS-Exchange-CrossTenant-originalarrivaltime: 24 Feb 2022 04:23:27.9681
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: QoqwRkyBkKg6ATGmeR50YpTUWc6/ayo4jts5MOQfeEUop+D8pAuwVuMzgc/UdnJtVFLaZG+HxuJMdG5pzIgtdQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB4758
X-Spam-Status: No, score=-1.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=no 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

> On Wed, Feb 23, 2022 at 03:49:09AM +0000, Akhil R wrote:
> > > Hi Akhil,
> > >
> > > On Mon, Feb 21, 2022 at 09:09:34PM +0530, Akhil R wrote:
> > > > Adding GPC DMA controller driver for Tegra. The driver supports dma
> > > > transfers between memory to memory, IO peripheral to memory and
> memory
> > > > to IO peripheral.
> > > >
> > > > Co-developed-by: Pavan Kunapuli <pkunapuli@nvidia.com>
> > > > Signed-off-by: Pavan Kunapuli <pkunapuli@nvidia.com>
> > > > Co-developed-by: Rajesh Gumasta <rgumasta@nvidia.com>
> > > > Signed-off-by: Rajesh Gumasta <rgumasta@nvidia.com>
> > > > Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> > > > Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
> > > > Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
> > > > ---
> > > >  drivers/dma/Kconfig            |   11 +
> > > >  drivers/dma/Makefile           |    1 +
> > > >  drivers/dma/tegra186-gpc-dma.c | 1507
> > > > ++++++++++++++++++++++++++++++++
> > > >  3 files changed, 1519 insertions(+)
> > > >  create mode 100644 drivers/dma/tegra186-gpc-dma.c
> > >
> > > <snip>
> > >
> > > > +static const struct __maybe_unused dev_pm_ops
> tegra_dma_dev_pm_ops =3D
> > > > +{
> > >
> > > The __maybe_unused cannot split the type ("struct dev_pm_ops") otherw=
ise
> it
> > > causes a clang warning:
> > >
> > > https://lore.kernel.org/r/202202221207.lQ53BwKp-lkp@intel.com/
> > >
> > > static const struct dev_pm_ops tegra_dma_dev_pm_ops __maybe_unused =
=3D
> {
> > >
> > > would look a litle better I think. However, is this attribute even ne=
eded? The
> > > variable is unconditionally used below, so there should be no warning=
 about
> it
> > > being unused?
> > >
> > > Cheers,
> > > Nathan
> > >
> > > > +     SET_SYSTEM_SLEEP_PM_OPS(tegra_dma_pm_suspend,
> > > > +tegra_dma_pm_resume) };
> > > > +
> > > > +static struct platform_driver tegra_dma_driver =3D {
> > > > +     .driver =3D {
> > > > +             .name   =3D "tegra-gpcdma",
> > > > +             .pm     =3D &tegra_dma_dev_pm_ops,
> > > > +             .of_match_table =3D tegra_dma_of_match,
> > > > +     },
> > > > +     .probe          =3D tegra_dma_probe,
> > > > +     .remove         =3D tegra_dma_remove,
> > > > +};
> > > > +
> > > > +module_platform_driver(tegra_dma_driver);
> > > > +
> > > > +MODULE_DESCRIPTION("NVIDIA Tegra GPC DMA Controller driver");
> > > > +MODULE_AUTHOR("Pavan Kunapuli <pkunapuli@nvidia.com>");
> > > > +MODULE_AUTHOR("Rajesh Gumasta <rgumasta@nvidia.com>");
> > > > +MODULE_LICENSE("GPL");
> > > > --
> > > > 2.17.1
> > > >
> > > >
> >
> > Hi Nathan,
> >
> > Thanks. Will update the same.
> >
> > I am getting notification for the below warning also.
> >
> > >> drivers/dma/tegra186-gpc-dma.c:898:53: warning: shift count >=3D wid=
th of
> type [-Wshift-count-overflow]
> >                            FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (=
dest >>
> 32));
> > https://lore.kernel.org/all/202202230559.bLOEMEUh-lkp@intel.com/
> >
> > I suppose, this is because it is compiled against a different ARCH othe=
r than
> arm64.
> > For arm64, the dma_addr_t is 64 bytes, and this warning does not occur.
> > Could this be ignored for now? If not, could you suggest a fix, if poss=
ible?
>=20
> I am not really familiar with the DMA API and dma_addr_t so I am not
> sure about a proper fix.
>=20
> You could cast dest to u64 to guarantee it is a type that can be shifted
> by 32 but that might not be right for CONFIG_PHYS_ADDR_T_64BIT=3Dn. If th=
e
> driver is not expected to run without CONFIG_PHYS_ADDR_T_64BIT, then
> this is probably fine.
>=20
> You could mark this driver 'depends on PHYS_ADDR_T_64BIT' if it cannot
> run with CONFIG_ARCH_TEGRA=3Dy + CONFIG_PHYS_ADDR_T_64BIT=3Dn but I do
> not
> see any other drivers that do that, which might mean that is not a
> proper fix.
>=20
> Please do not ignore the warning, as it will show up with ARCH=3Darm
> allmodconfig, which has -Werror enabled.
I see some drivers using 'depends on ARM64'. I guess probably we could
use that to avoid this warning. The driver is only supported for arm64 Tegr=
a
systems as of now.

Thanks,
Akhil