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Miller" Subject: Re: [PATCH v3 09/24] wfx: add hwio.c/hwio.h Date: Tue, 22 Dec 2020 22:02:09 +0100 Message-ID: <4279510.LvFx2qVVIh@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: SA9PR13CA0181.namprd13.prod.outlook.com (2603:10b6:806:26::6) 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 SA9PR13CA0181.namprd13.prod.outlook.com (2603:10b6:806:26::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3700.19 via Frontend Transport; Tue, 22 Dec 2020 21:02:12 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: e92abdc6-a474-49f7-c018-08d8a6bcdbfd X-MS-TrafficTypeDiagnostic: SA2PR11MB4988: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 2Jms4IfIg+E7TL/WqieQwR6kIenKxaVL/onwlr7ej6D8rTbYtOQQ9Y2JGYTkNLJlHD83nL6bQABbKQ93efPjtdetaOuw8sDZWpAy2dV1Q4/Z6v3Dbjta1SJRSIHrYCI+8yBRJ5JApNxmAx+Ltjdzi39I7Ix8vU6lo4l2GTMwaENLbzwJAKRMC8MwepYRa/ixXYzai2TP8+tQBeN+Bm0uJYCTyJTrUM0robdlyQBNBxLjz539i0MhJLxFpFcvTTFv8ZA8+QG+v0DOkLy2iXR9Cco1IOswaM8IvqOU78gkR9Gx1K13My6673eoJfFOjIFfaodppdSLNrDl05QeHb9ciKtwQd96c7CAEcYRcA/Qirs6vf5pl5yj8ZeyyZUU/i7EVzYXaU8LLBi01U1nuWCg1JzJ/ACmR5R5TRVt7zqun05wTktPVdnINtz8bXHWtpB9 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:(376002)(346002)(136003)(366004)(39850400004)(396003)(66574015)(4326008)(8936002)(6486002)(2906002)(6666004)(8676002)(36916002)(83380400001)(16526019)(26005)(110136005)(186003)(66556008)(6506007)(956004)(7416002)(33716001)(316002)(66476007)(86362001)(9686003)(54906003)(5660300002)(6512007)(478600001)(66946007)(52116002)(39026012);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?iso-8859-1?Q?QglQq2GR9IhKbtmd4ZG4Eg9LSLIsh7NdxHlKQ42SreptEPwG+VcOa9OB+3?= =?iso-8859-1?Q?uqibh72xrmnsQBfYOG2wiMfir8ztal4GM4dsHvKsh2PTbvbESFMWrc9wti?= =?iso-8859-1?Q?1Tk8M8wpjh9KsdXlq1FL0FUOAP9wZqQSKrmqMBPZzpG0JRj+rVV1En82/a?= =?iso-8859-1?Q?F/gcc38XE9nhfW4zjREGXFXyjbRUHCin5qDmNVJlOQaLEWDhyUi2ABWH1s?= =?iso-8859-1?Q?i8H93hgiP2usH13JbNaTnINIhpnK4dKKNkApQeKLeRcDrDfQdzyM/G0q86?= =?iso-8859-1?Q?E9C5KsK+sreSXa9Hgvc0SbZbxx+Ob43C23EXGUk8BYjZBnPwSlce0bbe23?= =?iso-8859-1?Q?S7RTLeAJbkHSX1hWVku2uON/jqRekXtXQtuFMgTMZP0oSDHe5+K/G6h+LR?= =?iso-8859-1?Q?UvxCrTIVkRNNNNU6jrHBTzKJhB5bWBvSDX12FFzhoI+WmuR0aiNqO85w5A?= =?iso-8859-1?Q?lZsagWyZjO7R04G5WHAmA7WbN2itgAS6pDXpXZSeb16dm8t5ze0wPTVYG5?= =?iso-8859-1?Q?IrBUQYF8li2/s2UsMpf9N9Lo59odmBUFx98hHJf56Sr6tF9NCIYLyCE+Ws?= =?iso-8859-1?Q?LCx1plNznB/sGgZPms52Qezb/9Bez6wSxntPFki9z9HgP/v98ajJ/EVQ06?= =?iso-8859-1?Q?assSVYBkj995HdQJTMM3B15G9kkxQi2ufoMLfD4Bu4Gk0N/Tc1kb0CmdJJ?= =?iso-8859-1?Q?wvxOLd5RRdrQ8cUetQASNQ2fQiDpCICmMLJdSccrEPbt4AlCuZVdgOXdQ3?= =?iso-8859-1?Q?6fK+ycF21LAgM/OfDfvT4sq5h5px3JdS/wmQF/d6gCdKdVPBqRFSBlKJmH?= =?iso-8859-1?Q?/txiZhIqJdRPtZROqZgHQZq570dP+j0eezFaoq3aUYwjF5UoedZMEgR4vY?= =?iso-8859-1?Q?jHSOXqwkZ/yYu2+e2+mMr4SXEwycT8wR35sCqbhUlPhW+4Ebq1IUs5t9he?= =?iso-8859-1?Q?kH2Wc/t2B4ufxoTh75b+XmePEztnjdt0kV/1TAxDcxFCjAFIK2ymF9lG/z?= =?iso-8859-1?Q?nkVcaaFautBZef6o/VJ47Loe8k6pVVEAlVtlOq?= 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: 22 Dec 2020 21:02:14.6598 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 54dbd822-5231-4b20-944d-6f4abcd541fb X-MS-Exchange-CrossTenant-Network-Message-Id: e92abdc6-a474-49f7-c018-08d8a6bcdbfd X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: iBJqPxn+nQ4EKOvhH6G45wWS0c+JDjopj+UyCiDcEF63+sfvc6V+7dT31rOPhWvRGMq+Ue22Txn7Lzu1DmH9pg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA2PR11MB4988 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tuesday 22 December 2020 16:27:01 CET Greg Kroah-Hartman wrote: >=20 > 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. Yes, I have learned this rule the hard way. There is no better way than a comment to warn the user that the argument will be used with a DMA? A Sparse annotation, for example? --=20 J=E9r=F4me Pouiller