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Received: from BN8PR12MB3587.namprd12.prod.outlook.com (2603:10b6:408:43::13) by CO6PR12MB5473.namprd12.prod.outlook.com (2603:10b6:303:13e::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4930.15; Thu, 27 Jan 2022 08:03:06 +0000 Received: from BN8PR12MB3587.namprd12.prod.outlook.com ([fe80::d8e7:e6b0:d63c:4a21]) by BN8PR12MB3587.namprd12.prod.outlook.com ([fe80::d8e7:e6b0:d63c:4a21%5]) with mapi id 15.20.4909.019; Thu, 27 Jan 2022 08:03:06 +0000 Message-ID: <3066c6a7-fc73-d34d-d209-a3ff6818dfb6@amd.com> Date: Thu, 27 Jan 2022 09:02:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 02/19] dma-buf-map: Add helper to initialize second map Content-Language: en-US To: Lucas De Marchi Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org References: <20220126203702.1784589-1-lucas.demarchi@intel.com> <20220126203702.1784589-3-lucas.demarchi@intel.com> <20220127075728.ygwgorhnrwaocdqv@ldmartin-desk2> From: =?UTF-8?Q?Christian_K=c3=b6nig?= In-Reply-To: <20220127075728.ygwgorhnrwaocdqv@ldmartin-desk2> Content-Type: text/plain; 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There is no importer and exporter here. Yeah, and exactly that's what I'm pointing out as problem here. You are using the inter driver framework for something internal to the driver. That is an absolutely clear NAK! We could discuss that, but you guys are just sending around patches to do this without any consensus that this is a good idea. Regards, Christian. > There is a role delegation on filling out and reading a buffer when > that buffer represents a struct layout. > > struct bla { >     int a; >     int b; >     int c; >     struct foo foo; >     struct bar bar; >     int d; > } > > > This implementation allows you to have: > >     fill_foo(struct dma_buf_map *bla_map) { ... } >     fill_bar(struct dma_buf_map *bla_map) { ... } > > and the first thing these do is to make sure the map it's pointing to > is relative to the struct it's supposed to write/read. Otherwise you're > suggesting everything to be relative to struct bla, or to do the same > I'm doing it, but IMO more prone to error: > >     struct dma_buf_map map = *bla_map; >     dma_buf_map_incr(map, offsetof(...)); > > IMO this construct is worse because at a point in time in the function > the map was pointing to the wrong thing the function was supposed to > read/write. > > It's also useful when the function has double duty, updating a global > part of the struct and a table inside it (see example in patch 6) > > thanks > Lucas De Marchi From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9C73EC433EF for ; Thu, 27 Jan 2022 08:03:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8CAD110E6A1; 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There is no importer and exporter here. Yeah, and exactly that's what I'm pointing out as problem here. You are using the inter driver framework for something internal to the driver. That is an absolutely clear NAK! We could discuss that, but you guys are just sending around patches to do this without any consensus that this is a good idea. Regards, Christian. > There is a role delegation on filling out and reading a buffer when > that buffer represents a struct layout. > > struct bla { >     int a; >     int b; >     int c; >     struct foo foo; >     struct bar bar; >     int d; > } > > > This implementation allows you to have: > >     fill_foo(struct dma_buf_map *bla_map) { ... } >     fill_bar(struct dma_buf_map *bla_map) { ... } > > and the first thing these do is to make sure the map it's pointing to > is relative to the struct it's supposed to write/read. Otherwise you're > suggesting everything to be relative to struct bla, or to do the same > I'm doing it, but IMO more prone to error: > >     struct dma_buf_map map = *bla_map; >     dma_buf_map_incr(map, offsetof(...)); > > IMO this construct is worse because at a point in time in the function > the map was pointing to the wrong thing the function was supposed to > read/write. > > It's also useful when the function has double duty, updating a global > part of the struct and a table inside it (see example in patch 6) > > thanks > Lucas De Marchi From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 40268C433EF for ; Thu, 27 Jan 2022 08:03:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DDF1310E750; 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Thu, 27 Jan 2022 08:03:06 +0000 Received: from BN8PR12MB3587.namprd12.prod.outlook.com ([fe80::d8e7:e6b0:d63c:4a21]) by BN8PR12MB3587.namprd12.prod.outlook.com ([fe80::d8e7:e6b0:d63c:4a21%5]) with mapi id 15.20.4909.019; Thu, 27 Jan 2022 08:03:06 +0000 Message-ID: <3066c6a7-fc73-d34d-d209-a3ff6818dfb6@amd.com> Date: Thu, 27 Jan 2022 09:02:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-US To: Lucas De Marchi References: <20220126203702.1784589-1-lucas.demarchi@intel.com> <20220126203702.1784589-3-lucas.demarchi@intel.com> <20220127075728.ygwgorhnrwaocdqv@ldmartin-desk2> From: =?UTF-8?Q?Christian_K=c3=b6nig?= In-Reply-To: <20220127075728.ygwgorhnrwaocdqv@ldmartin-desk2> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: AS8P250CA0029.EURP250.PROD.OUTLOOK.COM (2603:10a6:20b:330::34) To BN8PR12MB3587.namprd12.prod.outlook.com (2603:10b6:408:43::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9e0245dc-f281-44e1-032e-08d9e16b735e X-MS-TrafficTypeDiagnostic: CO6PR12MB5473:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; 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There is no importer and exporter here. Yeah, and exactly that's what I'm pointing out as problem here. You are using the inter driver framework for something internal to the driver. That is an absolutely clear NAK! We could discuss that, but you guys are just sending around patches to do this without any consensus that this is a good idea. Regards, Christian. > There is a role delegation on filling out and reading a buffer when > that buffer represents a struct layout. > > struct bla { >     int a; >     int b; >     int c; >     struct foo foo; >     struct bar bar; >     int d; > } > > > This implementation allows you to have: > >     fill_foo(struct dma_buf_map *bla_map) { ... } >     fill_bar(struct dma_buf_map *bla_map) { ... } > > and the first thing these do is to make sure the map it's pointing to > is relative to the struct it's supposed to write/read. Otherwise you're > suggesting everything to be relative to struct bla, or to do the same > I'm doing it, but IMO more prone to error: > >     struct dma_buf_map map = *bla_map; >     dma_buf_map_incr(map, offsetof(...)); > > IMO this construct is worse because at a point in time in the function > the map was pointing to the wrong thing the function was supposed to > read/write. > > It's also useful when the function has double duty, updating a global > part of the struct and a table inside it (see example in patch 6) > > thanks > Lucas De Marchi