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Miller" Subject: Re: [PATCH v3 09/24] wfx: add hwio.c/hwio.h Date: Wed, 23 Dec 2020 09:01:33 +0100 Message-ID: <5567602.MhkbZ0Pkbq@pc-42> Organization: Silicon Labs In-Reply-To: References: <20201104155207.128076-1-Jerome.Pouiller@silabs.com> <87lfdp98rw.fsf@codeaurora.org> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" X-Originating-IP: [82.67.86.106] X-ClientProxiedBy: SN4PR0701CA0042.namprd07.prod.outlook.com (2603:10b6:803:2d::16) To SN6PR11MB2718.namprd11.prod.outlook.com (2603:10b6:805:63::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from pc-42.localnet (82.67.86.106) by SN4PR0701CA0042.namprd07.prod.outlook.com (2603:10b6:803:2d::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3700.27 via Frontend Transport; Wed, 23 Dec 2020 08:01:36 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 34ee1a89-afaa-4783-732e-08d8a718f9c0 X-MS-TrafficTypeDiagnostic: SN6PR11MB2653: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7219; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: k7Bm05TVa6l0sZbUDDcgk9562codqJyRcbxT/kIw7K1frgz8pzLJd+LU0qhkIk4Hp9hbqDTxo9Gee+l7DXufQfgMbZvtGtaU+EYQf1S7p5rT6swbb00y0bdqQa8JCGe2YRBvjV9HYxFzgGtAyZzKpK5z+mAGkffzCXmqoFJ9wjDXXecd5aSRxNo2wxbcIyWMKlr8l5DRH+alQVFbdN7ttwxVZgkDFS5v+88pNNPEzwCl+Le/7wXb+pw/6MQe8guLdMUKJgzwyeoF0At3UkopRgwYD87i5b/FKsqqBTHvUdTVicmY+Fw8yyXCVHKEZQx/NtnY/+Ujm7cHMPz3u9WZqzs00LTLtdBdpeIiNFM1XA3AYUUMMq8MlqSrAW47TgDUdhM1Qc0PHNmOncibpzX8oAxtCpclaqBRuZTV86LweWgwOb3OBT7qaBYtk9oSn53S X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN6PR11MB2718.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(136003)(366004)(39850400004)(376002)(346002)(396003)(2906002)(5660300002)(8676002)(6666004)(316002)(6512007)(110136005)(186003)(66946007)(9686003)(16526019)(54906003)(66574015)(33716001)(6486002)(83380400001)(36916002)(66556008)(66476007)(52116002)(26005)(478600001)(4326008)(6506007)(8936002)(7416002)(956004)(86362001)(39026012);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?iso-8859-1?Q?j1KjEDULDNLkpMXVIS4vBiaHpcy3z6+j00d8qlEa4AqGTDE1hHDhFR5qSd?= =?iso-8859-1?Q?hMNbX+HWXLxJV3PDn/TGOZ5GzstvZEGTXYiD0r8eOVPAh05x0OUZZPh9hS?= =?iso-8859-1?Q?umLh+YPUX7lct99MccwvbhPtrOXgjactSkdw/tIWtBQdzGL6kiw/edkyGo?= =?iso-8859-1?Q?IV5DvEvtkW2Q33f6w5NDrB8/DaNeHODmsJRsF+hM0Lqp0frZZj9ACIOiR6?= =?iso-8859-1?Q?d/+bCBFH09ROdtzv3QjOYKBLxckmaKRdpu1v4CP8q1m8EotjXdzQf8S4GV?= =?iso-8859-1?Q?0UuU5oz/ujSHWQ7sbm2/WnQFwtOWnUqVxyGRv3lc0aC5qZfC7Fkycf7Y9J?= =?iso-8859-1?Q?mnp+nD3+Jsxokw9tXBVl9RFt2xqYoE10awOyPQfDGZu7G4SXsSWBAIkXG7?= =?iso-8859-1?Q?UOmQAf90bDkNfNTVpVU8mRcABZQI+jOfuj3SrhhzuKMtZ7zw+D2X5OeNN1?= =?iso-8859-1?Q?DJl4AVcOzBsi0vxMBHDsUtJv080RsCc2pErtkamiqiFnPc7EHAuXOG3azO?= =?iso-8859-1?Q?WYMHHVJB9vQiUXUvWgi5ZPxRhjhbz0gLv9qGcFTh2+LLd+eNKiRwadaNYx?= =?iso-8859-1?Q?ko2gRJTT+qAiNqVgqYMai3fgDBSG4STBF9SU26yDDrrXmyKEY+VxA58nxX?= =?iso-8859-1?Q?7LkoFVyanEUK2/kCv7GtGGqHXHw9NRhTIMjkIS46029qk0YTdpEcXZU4Lt?= =?iso-8859-1?Q?JpvAksm57mLUBNLP1fxwe5F97Ye4XUS3aEjM4zbe/StcnmTD6HkjpkLcsW?= =?iso-8859-1?Q?lWf8GQY9Xe8WO9ebcTXH0bgonm4+cT4sFB9vzin/lVy+S46FXK1i0rI9py?= =?iso-8859-1?Q?D2Bjs6O/WZ5rh9MIqeWPx6ZJRIeu0Mouv5c5OTDTnmq132j/WmibF7P5ku?= =?iso-8859-1?Q?HYWaWt6QlRlE/v08HR+TVMtESHlvAiDrk2c4gIwmbRI1W+tLoJii3pz70A?= =?iso-8859-1?Q?fOs8tlMtkAWZc96vxQYgvLBVMGF1xenU2kCffde7aL10rQ910Y64jGmUMC?= =?iso-8859-1?Q?PYM9qVzyCgc6buvi4=3D?= X-OriginatorOrg: silabs.com X-MS-Exchange-CrossTenant-AuthSource: SN6PR11MB2718.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Dec 2020 08:01:38.2748 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 54dbd822-5231-4b20-944d-6f4abcd541fb X-MS-Exchange-CrossTenant-Network-Message-Id: 34ee1a89-afaa-4783-732e-08d8a718f9c0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: hopm7uaW1xAbroXUKPX0aPno3Cdjbj16CONACu6xDx9iVj+tlvnseK7OqN1FWrxxfoxlvnMOeCUV7LWJhTzuOw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR11MB2653 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Tuesday 22 December 2020 16:27:01 CET Greg Kroah-Hartman wrote: > On Tue, Dec 22, 2020 at 05:10:11PM +0200, Kalle Valo wrote: > > Jerome Pouiller writes: > > > > > +/* > > > + * Internal helpers. > > > + * > > > + * About CONFIG_VMAP_STACK: > > > + * When CONFIG_VMAP_STACK is enabled, it is not possible to run DMA = on stack > > > + * allocated data. Functions below that work with registers (aka fun= ctions > > > + * ending with "32") automatically reallocate buffers with kmalloc. = However, > > > + * functions that work with arbitrary length buffers let's caller to= handle > > > + * memory location. In doubt, enable CONFIG_DEBUG_SG to detect badly= located > > > + * buffer. > > > + */ > > > > This sounds very hacky to me, I have understood that you should never > > use stack with DMA. >=20 > You should never do that because some platforms do not support it, so no > driver should ever try to do that as they do not know what platform they > are running on. Just to be curious, why these platforms don't support DMA in a stack allocated area? If the memory is contiguous (=3D not vmalloced), correctly aligned and in the first 4GB of physical memory, it should be sufficient, shouldn't?=20 --=20 J=E9r=F4me Pouiller