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Wed, 25 Nov 2020 09:19:19 +0000 Subject: Re: [PATCH v1] spi: fix client driver breakages when using GPIO descriptors To: Mark Brown , Linus Walleij Cc: Rob Herring , Sven Van Asbroeck , Andy Shevchenko , Jonathan Cameron , Simon Han , Lukas Wunner , linux-spi , Linux Kernel Mailing List , nd References: <20201106150706.29089-1-TheSven73@gmail.com> <20201111123327.GB4847@sirena.org.uk> <20201116210632.GJ4739@sirena.org.uk> <20201118114049.GA4827@sirena.org.uk> From: Grant Likely Message-ID: <9c7aee21-0d08-9092-acdd-93477ed17dba@arm.com> Date: Wed, 25 Nov 2020 09:19:15 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 In-Reply-To: <20201118114049.GA4827@sirena.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [94.196.85.203] X-ClientProxiedBy: LNXP265CA0090.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:76::30) To DB8PR08MB4010.eurprd08.prod.outlook.com (2603:10a6:10:ab::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.16.178] (94.196.85.203) by LNXP265CA0090.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:76::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3611.20 via Frontend Transport; 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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Nov 2020 09:19:28.9924 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c4ec06fe-09ff-4312-e63b-08d891233620 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[63.35.35.123];Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com] X-MS-Exchange-CrossTenant-AuthSource: DB5EUR03FT055.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR08MB4151 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org On 18/11/2020 11:40, Mark Brown wrote: > On Wed, Nov 18, 2020 at 02:03:41AM +0100, Linus Walleij wrote: >> On Mon, Nov 16, 2020 at 10:06 PM Mark Brown wrote: > >>> I think the main push in the other direction has always been people who >>> want to not have to write a driver at all and put absolutely everything >>> into DT which has scaling issues :/ > >> What I can't understand is what gave them that idea. > >> This thing looks like a dream to these people for example: >> https://gist.github.com/Minecrell/56c2b20118ba00a9723f0785301bc5ec#file-dsi_panel_s6e88a0_ams452ef01_qhd_octa_video-dtsi >> And it looks like a nightmare to me. > >> (There is even a tool to convert this description into a proper display >> driver now.) > >> It just seems to be one of those golden hammer things: everything >> start to look like nails. > > What people think they were sold was the idea that they shouldn't have > to write driver code or upstream things, something with more AML like > capabilities (not realising that AML works partly because ACPI hugely > constrains system design). And is also untrue. AML only provides an API abstraction for a specific power management model. All the actual driving of the device still requires driver code and requires reading devices-specific properties out of the ACPI node. g.