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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A95B5C02185 for ; Sat, 18 Jan 2025 08:39:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zKuPDlOMPDO5oGq08bHFWi7TOK0868onJ3Gwccm4HFo=; b=rgMIQDxnhw9wrkpHEYt4efg1gL UcwHHXwLAafVQ3PPqZpFhd1Zq/O9IP615mo1GcJFupMxrtlwtUS69yLXVVYudGr5Bk29JkxpjH9Il I11k564kp48xIoNvTdS0AoAdFPukTQy8hmeG93B9/lwN5Q1k9LvBJOm9TX4VVxugHkfZNRIwYpyxi TW2ptraN4S5V1ehfM4JB0BvD8Me6HNzjEi9iGo9cmFefJEottNrDlsjx3CdjQ5jQpzVBKqgsDWB/B YMel/NOVZbwmqJa9fmYHqiP0CC4pJZlqW4eisITGYIjQnK8fXPctTReaVLFnXh5nSaPtZ+Rpsoqap 1gTs1PAw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tZ4Lu-000000022Yv-2lc1; Sat, 18 Jan 2025 08:38:46 +0000 Received: from nyc.source.kernel.org ([2604:1380:45d1:ec00::3]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tZ4Kd-000000022SY-3Qna; Sat, 18 Jan 2025 08:37:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 21E89A41462; Sat, 18 Jan 2025 08:35:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E47F9C4CED1; Sat, 18 Jan 2025 08:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737189446; bh=tvFTbNI16dWEiQ0a1DxdbCn/gVCZieFS78UcbDryCxo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Vt5NL/gKLDm/Wrkb8SUMOQwwRjr3aRNsqTWpIaF7cbZFBb+1wBA2Wg0AIVfoKm9Yc 0rKfOW0O3zSXXRm0tNacj4hNeS26RZs6mtzWuqRs6O0all5P+x6RuvTP0SjFkgpN94 HKFr21WH7OBJaH87vQ4BVs6yE9SHgbd9cnFKygRWCtOO9a5mVIf0EI83Geh4NNWuzx tDKNXIw3SQG3UMPWDv9zWTSh2AeLIT7yVBLrlaOVqtRwXD+8m0480YI49CEl2k1SKN u+yA07OjzyiIyG+4kLTM84IDJsviaBsh3fJN6o5pNljCFhmQ5ymSeeMDD/ROcGwVLd G+MMTBLmFywvg== Message-ID: Date: Sat, 18 Jan 2025 09:37:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/12] dt-bindings: display: mediatek: add EXDMA yaml for MT8196 To: =?UTF-8?B?UGF1bC1wbCBDaGVuICjpmbPmn4/pnJYp?= , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "chunkuang.hu@kernel.org" , AngeloGioacchino Del Regno Cc: =?UTF-8?B?U3VubnkgU2hlbiAo5rKI5aeN5aeNKQ==?= , =?UTF-8?B?U2lyaXVzIFdhbmcgKOeOi+eak+aYsSk=?= , =?UTF-8?B?TmFuY3kgTGluICjmnpfmrKPonqIp?= , =?UTF-8?B?WGlhbmRvbmcgV2FuZyAo546L5YWI5YasKQ==?= , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Project_Global_Chrome_Upstream_Group , "linux-mediatek@lists.infradead.org" , =?UTF-8?B?SmFzb24tSkggTGluICjmnpfnnb/npaUp?= , "devicetree@vger.kernel.org" , "fshao@chromium.org" , "p.zabel@pengutronix.de" , =?UTF-8?B?U2luZ28gQ2hhbmcgKOW8teiIiOWciyk=?= , "linux-arm-kernel@lists.infradead.org" , "matthias.bgg@gmail.com" , "treapking@chromium.org" References: <20250110123835.2719824-1-paul-pl.chen@mediatek.com> <20250110123835.2719824-4-paul-pl.chen@mediatek.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250118_003727_981100_8BF2BDDF X-CRM114-Status: GOOD ( 16.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 17/01/2025 11:36, Paul-pl Chen (陳柏霖) wrote: >>> b/Documentation/devicetree/bindings/display/mediatek/mediatek,exdma >>> .yaml >> >> Filename matching compatible. >> >> Why is this in display? DMA goes to dma. > > Hi Krzysztof , > > Regarding the issue of the EXDMA driver, we have conducted an internal > survey of drivers under the DMA subsystem. We found that EXDMA operates I did not talk about driver. I talked about this patch. Look at patch title - it starts with dt-bindings. Is here anything about driver? No. Why do we talk about driver? > differently from typical DMA drivers, and therefore we believe that the > EXDMA driver may not be suitable to be placed under the > driver/mediatek/drm directory. The main reasons are as follows: > > (1)No Memory Allocation within EXDMA Engine: > The EXDMA engine does not perform memory allocation operations itself. > Instead, it relies on GEM (Graphics Execution Manager) to allocate > memory.Traditional DMA drivers often handle their own memory > allocations, but in the case of EXDMA, memory management is delegated > to GEM. > > (2)Primary Task of EXDMA: > The main function of EXDMA is to transfer buffers allocated by GEM to > the subsequent display pipeline. > EXDMA serves as a bridge between memory allocated by GEM and the > display components, rather than acting as a general-purpose DMA engine. > Based on the points above, we have decided to place the EXDMA driver > under the DRM display subsystem rather than under the DMA subsystem. I don't care if it uses GEM or kernel allocator or even 3rd party allocator. The question is: what is this device? If it is performing DMA, then it should be placed in "dma" directory. The rdma was placed differently but as you can easily check: it was never acked/reviewed, so don't use it as an example. Of course if it does not perform DMA, then it should not be in dma, but then I don't agree on using dma-cells here and anything like that in the driver. Best regards, Krzysztof 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 8F794C02187 for ; Sat, 18 Jan 2025 08:38:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:To:Subject :MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zKuPDlOMPDO5oGq08bHFWi7TOK0868onJ3Gwccm4HFo=; b=kCWmbc4R7m5rWq 0oNUCHbazFrD3fceq5e6cVxbt5OI4ooeYWaCnD0sG5sPHmVv10HaOgn/DW2x6c93AUeOAStY9NhYi dNfh2HWNnbfAMlMGLuBPWzBgfe+Q2ZhmPYDHppValJZWf4vTKzL+9Y1XNjkXw+eYeplVZ2va79Fiy ShoNLEAQH8EfE6XqoCzZAxVJLR4XlFeMD643cRXeJzHP/dC0l9KEi92DlbWo8wyUttceVmZTFlohy 3zH7BDvXE3s0PuUEACuqMvTwv5+vfnYXCd2JSwJnB7ENEVb7hcV1bvYktelgjMcbZTxf4zWgvyz4c bwInAP/pre/JGNIEr1lA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tZ4Lv-000000022ZA-0dkL; Sat, 18 Jan 2025 08:38:47 +0000 Received: from nyc.source.kernel.org ([2604:1380:45d1:ec00::3]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tZ4Kd-000000022SY-3Qna; Sat, 18 Jan 2025 08:37:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 21E89A41462; Sat, 18 Jan 2025 08:35:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E47F9C4CED1; Sat, 18 Jan 2025 08:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737189446; bh=tvFTbNI16dWEiQ0a1DxdbCn/gVCZieFS78UcbDryCxo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Vt5NL/gKLDm/Wrkb8SUMOQwwRjr3aRNsqTWpIaF7cbZFBb+1wBA2Wg0AIVfoKm9Yc 0rKfOW0O3zSXXRm0tNacj4hNeS26RZs6mtzWuqRs6O0all5P+x6RuvTP0SjFkgpN94 HKFr21WH7OBJaH87vQ4BVs6yE9SHgbd9cnFKygRWCtOO9a5mVIf0EI83Geh4NNWuzx tDKNXIw3SQG3UMPWDv9zWTSh2AeLIT7yVBLrlaOVqtRwXD+8m0480YI49CEl2k1SKN u+yA07OjzyiIyG+4kLTM84IDJsviaBsh3fJN6o5pNljCFhmQ5ymSeeMDD/ROcGwVLd G+MMTBLmFywvg== Message-ID: Date: Sat, 18 Jan 2025 09:37:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/12] dt-bindings: display: mediatek: add EXDMA yaml for MT8196 To: =?UTF-8?B?UGF1bC1wbCBDaGVuICjpmbPmn4/pnJYp?= , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "chunkuang.hu@kernel.org" , AngeloGioacchino Del Regno References: <20250110123835.2719824-1-paul-pl.chen@mediatek.com> <20250110123835.2719824-4-paul-pl.chen@mediatek.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250118_003727_981100_8BF2BDDF X-CRM114-Status: GOOD ( 16.99 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "devicetree@vger.kernel.org" , =?UTF-8?B?WGlhbmRvbmcgV2FuZyAo546L5YWI5YasKQ==?= , =?UTF-8?B?SmFzb24tSkggTGluICjmnpfnnb/npaUp?= , =?UTF-8?B?U2luZ28gQ2hhbmcgKOW8teiIiOWciyk=?= , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Project_Global_Chrome_Upstream_Group , "treapking@chromium.org" , =?UTF-8?B?TmFuY3kgTGluICjmnpfmrKPonqIp?= , "linux-mediatek@lists.infradead.org" , =?UTF-8?B?U3VubnkgU2hlbiAo5rKI5aeN5aeNKQ==?= , "p.zabel@pengutronix.de" , =?UTF-8?B?U2lyaXVzIFdhbmcgKOeOi+eak+aYsSk=?= , "matthias.bgg@gmail.com" , "linux-arm-kernel@lists.infradead.org" Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On 17/01/2025 11:36, Paul-pl Chen (陳柏霖) wrote: >>> b/Documentation/devicetree/bindings/display/mediatek/mediatek,exdma >>> .yaml >> >> Filename matching compatible. >> >> Why is this in display? DMA goes to dma. > > Hi Krzysztof , > > Regarding the issue of the EXDMA driver, we have conducted an internal > survey of drivers under the DMA subsystem. We found that EXDMA operates I did not talk about driver. I talked about this patch. Look at patch title - it starts with dt-bindings. Is here anything about driver? No. Why do we talk about driver? > differently from typical DMA drivers, and therefore we believe that the > EXDMA driver may not be suitable to be placed under the > driver/mediatek/drm directory. The main reasons are as follows: > > (1)No Memory Allocation within EXDMA Engine: > The EXDMA engine does not perform memory allocation operations itself. > Instead, it relies on GEM (Graphics Execution Manager) to allocate > memory.Traditional DMA drivers often handle their own memory > allocations, but in the case of EXDMA, memory management is delegated > to GEM. > > (2)Primary Task of EXDMA: > The main function of EXDMA is to transfer buffers allocated by GEM to > the subsequent display pipeline. > EXDMA serves as a bridge between memory allocated by GEM and the > display components, rather than acting as a general-purpose DMA engine. > Based on the points above, we have decided to place the EXDMA driver > under the DRM display subsystem rather than under the DMA subsystem. I don't care if it uses GEM or kernel allocator or even 3rd party allocator. The question is: what is this device? If it is performing DMA, then it should be placed in "dma" directory. The rdma was placed differently but as you can easily check: it was never acked/reviewed, so don't use it as an example. Of course if it does not perform DMA, then it should not be in dma, but then I don't agree on using dma-cells here and anything like that in the driver. Best regards, Krzysztof