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Mon, 6 Sep 2021 06:56:13 +0000 Subject: Re: [PATCH v3.1 2/3] iio: chemical: Add Senseair Sunrise 006-0-007 driver From: Peter Rosin To: Jonathan Cameron , Jacopo Mondi Cc: Lars-Peter Clausen , Andy Shevchenko , Matt Ranostay , Magnus Damm , linux-iio@vger.kernel.org, linux-i2c@vger.kernel.org, Wolfram Sang References: <20210822184927.94673-3-jacopo@jmondi.org> <20210823073639.13688-1-jacopo@jmondi.org> <20210829175413.7ce30bfa@jic23-huawei> <20210830162051.rjqlhwvtguaivt3p@uno.localdomain> <20210830181117.6808f085@jic23-huawei> <20210831074011.d6f5rsix2mgxqba5@uno.localdomain> <20210905110429.34763e30@jic23-huawei> <5e9dce02-2884-d91e-78ef-da2f32258ea3@axentia.se> Organization: Axentia Technologies AB Message-ID: <02f30a94-4b37-fb7a-da7f-d557fb22b431@axentia.se> Date: Mon, 6 Sep 2021 08:56:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 In-Reply-To: <5e9dce02-2884-d91e-78ef-da2f32258ea3@axentia.se> Content-Type: text/plain; charset=utf-8 Content-Language: sv-SE Content-Transfer-Encoding: 7bit X-ClientProxiedBy: HE1PR0502CA0003.eurprd05.prod.outlook.com (2603:10a6:3:e3::13) To DB8PR02MB5482.eurprd02.prod.outlook.com (2603:10a6:10:eb::29) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.13.3] (85.229.94.233) by HE1PR0502CA0003.eurprd05.prod.outlook.com (2603:10a6:3:e3::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4478.17 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?c1pBbHJSVWlWWGZKbkF2d0V5L0FkQ09xR2IrQTRDNjlJa0FPaklmckJXWlRj?= =?utf-8?B?Y0ZGSlhIYm1WM2pGWWtwZW1iekF0M3p5R3pCUW5mZmlsSzZUSC9yU0d5ZW1Y?= =?utf-8?B?SGxvOXBramFjTEZmVFNKSkQ1b0U1dnhvWU1MT3VaVFNoQmNhZTBnVnpzRCt3?= =?utf-8?B?aHM2ditiVXpaV29QYlNObkRYTWtCOGl6Sit0OWY3SnJzS1NTYnZXRTdMVzBE?= =?utf-8?B?MkpZNUJYdDJDak9kZkpncXdBOFBTZHJKR2tDWFcrTkFpVEFodnpyT0poblc0?= =?utf-8?B?ZjNWOWc5RkllU2RndUdzL0ozYW9EeVZNcnBQdDFsK2Y4RmNKak1QSUVEaFZU?= =?utf-8?B?VU13TnFkUEMrNGpoSy9qUmVGajZzSGVBV1BDbm5KNlh5b1M0VDByVFJ0TEhn?= =?utf-8?B?d3N6a0FaVVJSMzVKMy9taFh4cVp1ckJaaHpkZEx0UkN3MHJlYW9jL0JxQ0Ny?= =?utf-8?B?K1NVb3d0cmJyMDRTVUM0VmNvYWp2TkpROGVrZG1hNGxTN2FzY1d1Rkl3Y3NV?= =?utf-8?B?c0NaN1VhQUd4V2hGYWx2WURHWEMvYVFCRFdEVWZlNjArSGhQeTR1VXY4N0FZ?= =?utf-8?B?WmsvZm1LZlJURmdaNHhVVDUxNXdxclRBd2dWYjMzWTVEbFpHamp6cUpYMVJL?= =?utf-8?B?UVFpd1Q0dVJvUlpTekxVd2lBd1RTcjdubURMRFNzQXV4OTh5WTdOWGFONDlR?= =?utf-8?B?amJWS01VZXRtUDFMSTlHR1JycU03YWNIL2FkSE03cmEyK08yS1NsbHpDNm9Y?= =?utf-8?B?Y2hGUmlWK1RtNmdmQzdrbHE5dmcwUTRVRHk1MzRGMlhEYkNiSkVlTit2ZXlS?= =?utf-8?B?YlBFWHdOM051OERmTlY5L1o4RFNhNFlyd2JUeWVtWlB3YkJVZVM4ZmZmUXJH?= =?utf-8?B?NG1XZ28wS1o1Y0RKTUtJUzFTWm5TWDVmODd3MlVRaGZNQ3NjZEttWjhpT1c0?= =?utf-8?B?RW5ubE0rNERBU1Q4aDlqM2dKV0MwakJOMEhnVFhuaEgwVjdXTzVFUVA2VWQx?= =?utf-8?B?dWRYOGVZT0d0dVloYUR4d2NGNmdrSWVEN0JaekJ6eVMzcVpZOEwrakMxaU8z?= =?utf-8?B?QmFGMXR6MVNtU0xlUmZaU0ptdGNMNzJUNERnalpYRTByUDhOa1Z1eFlXNDQ4?= =?utf-8?B?dXdzcmoyaVduZXhtRlpSU1RFbng2YjcrUjhEMUFCaFkwQjlYbDAvOGhIek5a?= =?utf-8?B?U0hCRGZmd2lUWFR6WTVQOU9CTnhPdmVMQ3dlQWdrc3pIdzJMblJyc3JWSkNa?= =?utf-8?B?N0NVQ0tUWndpOGREQ0RHcHFteFc2alFMWERPV3B0cFpBcFVZcC8wV0xaZjRW?= =?utf-8?B?OCs1Wkw4TDVYWXAvNC8wZFgvQTc3d0RGNytBaERSMTJUdnZiem5lRXZyOUFV?= =?utf-8?B?MjBoR1FXT1liMlQrR1dCZHBrWEp3NUx3VnZmaGlxZDNuWVlmSjNiVStxVzMy?= =?utf-8?B?djVQRGhiLzZZenhKa1YwcU1VUFgvWXhJUVdva2pseTgyNmYxZ3Fud3lsdS9M?= =?utf-8?B?ckJLR1pNbHFmc2JCbHIxbm4rWWZ0Nkt3T3VTT2hMS1VEVGxiWEl0OWYrY05a?= =?utf-8?B?NVVJRC9jUGZJbkthb1liRk02b0Q0aVlqMWF3UWFFTEtvelN1aHRhOHkxRHpk?= =?utf-8?B?YmFKNDBXY1pwRU5rNk9OTlZoU1ZKemdpd3JJc0JUdmo4amVkaTd1SHo1aEFE?= =?utf-8?B?cXVLTm05cElySlNEUzYxNElGblBUVndnT21ibC94NUtTMVR5MlBCYStRb0Yr?= =?utf-8?Q?AwQdntsTiUQiIzH85eNUlcOJJcMTSSqKqgMAZtj?= X-OriginatorOrg: axentia.se X-MS-Exchange-CrossTenant-Network-Message-Id: 826af44b-8fd1-4f60-ca91-08d971036a2d X-MS-Exchange-CrossTenant-AuthSource: DB8PR02MB5482.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Sep 2021 06:56:13.1591 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4ee68585-03e1-4785-942a-df9c1871a234 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 3q34mPUOwadojBxSpbTw7Y4Xh/Z8QYnTpLpK6jtvVaBRrEc+f3wB8xSEXabcvtSU X-MS-Exchange-Transport-CrossTenantHeadersStamped: DBAPR02MB6248 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 2021-09-06 01:03, Peter Rosin wrote: > On 2021-09-05 12:04, Jonathan Cameron wrote: >> On Tue, 31 Aug 2021 09:40:11 +0200 >> Jacopo Mondi wrote: >> >>> Hi Jonathan, >>> two more clarification requests, sorry to bother :) >> No problem. First one: No idea +CC wolfram and i2c list. >>> >>> On Mon, Aug 30, 2021 at 06:11:17PM +0100, Jonathan Cameron wrote: >>>> On Mon, 30 Aug 2021 18:20:51 +0200 >>>>>>> +static int sunrise_write_word(struct sunrise_dev *sunrise, u8 reg, u16 data) >>>>>>> +{ >>>>>>> + __be16 be_data = cpu_to_be16(data); >>>>>>> + int ret; >>>>>>> + >>>>>>> + sunrise_wakeup(sunrise); >>>>>> >>>>>> Hmm. Technically there isn't anything stopping another user of the i2c bus sneaking in >>>>>> between the wakeup and the following command. That would make the device going back >>>>>> to sleep a lot more likely. I can't off the top of my head remember if regmap lets >>>>>> you lock the bus. If not, you'll have to use the underlying i2c bus locking functions. >>>>>> https://elixir.bootlin.com/linux/latest/source/drivers/iio/temperature/mlx90614.c#L432 >>>>>> gives an example. Forgot to mention, regmap does let you do that. See e.g. drivers/media/dvb-frontends/rtl2830.c which wraps regmap_update_bits, regmap_bulk_write and regmap_bulk_read within a local I2C segment lock along with a special regmap_bus that does unlocked I2C trasfers. I think the driver does this because it has an I2C gate that needs to be opened with a regmap interaction that in turn needs to be back to back with the "real" regmap access, or else the gate closes again. Cheers, Peter