From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7ACD42836F; Fri, 15 Aug 2025 08:32:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755246726; cv=none; b=FCkzRitowD0OLjitKkKR0/fac6EKihHkW4FUXv/OpFT8bVEacpMFouEvb/ZjpQ8L4/TobG8RY/GmIeeVxFuIUGTMea4ql1UsXC7Tmg9q0VrEGwVZRhj+4n5qxpbSoczaYL9ok0+KBuBh5Fn69PHgMWMoRFgI93io1a1NcdZkbjY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755246726; c=relaxed/simple; bh=9+8DBXXTptKn2ZWjjVXEiRdMpDFZWM3gMPQi3jbFQpo=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=T4SxRqEKs7aQzZgZmgMETsdetP9PIao+qcLMwtWvKkH7oNmgpx5o2do+p1dmk71QMO6qDan3UhYMrl6Tu0sAyOSU1lmYvgilm+qIkZ1dLi4VBlT90M8kd4nfH3LesEqfShG2zI99hi7qnqlkn9KfbJ2fApY28IZZ8iltLClhHc0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gGKmw4Ap; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gGKmw4Ap" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DB08C4CEEB; Fri, 15 Aug 2025 08:32:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755246726; bh=9+8DBXXTptKn2ZWjjVXEiRdMpDFZWM3gMPQi3jbFQpo=; h=Date:Subject:To:References:From:In-Reply-To:From; b=gGKmw4ApnoAQgJHg1XK47rQAiNYIEjjgwwIhqNFK6ERKqG4u7IVccY2UFnrMSBStm sz5q3KxAdYXKTy0p3/TL/9sGVsMn1NNgBM6ouiShqAuSiC6guZ22DOg20vQr4P9fFW SXezbAyppmwK64z0mTKArt4u2eRAVONKUFi1YPAIMnALVbxDeksWetbZc3splGLGEK oyhLYG66x+B/TaT2jVFT/jhxX5oOmmjtrXnrJhNcT0fIrgIn9NkHgv/kZqnv/mRy8Q Y3NhUsU/A2QPeCiYFQRnUt8gMpkON08DjuZ/ZWa7p71U806+3jZbdHjxbRVKmVQfeF sRWEZeDtelq3Q== Message-ID: Date: Fri, 15 Aug 2025 10:32:01 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] dt-bindings: lgm-dma: Added intel,dma-sw-desc property. To: Yi xin Zhu , "vkoul@kernel.org" , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "p.zabel@pengutronix.de" , "kees@kernel.org" , "dave.jiang@intel.com" , "av2082000@gmail.com" , "dmaengine@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20250808032243.3796335-1-yzhu@maxlinear.com> <32a2ec88-b9b8-4c4d-9836-838702e4e136@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; keydata= xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzSVLcnp5c3p0b2Yg S296bG93c2tpIDxrcnprQGtlcm5lbC5vcmc+wsGVBBMBCgA/AhsDBgsJCAcDAgYVCAIJCgsE FgIDAQIeAQIXgBYhBJvQfg4MUfjVlne3VBuTQ307QWKbBQJoF1BKBQkWlnSaAAoJEBuTQ307 QWKbHukP/3t4tRp/bvDnxJfmNdNVn0gv9ep3L39IntPalBFwRKytqeQkzAju0whYWg+R/rwp +r2I1Fzwt7+PTjsnMFlh1AZxGDmP5MFkzVsMnfX1lGiXhYSOMP97XL6R1QSXxaWOpGNCDaUl ajorB0lJDcC0q3xAdwzRConxYVhlgmTrRiD8oLlSCD5baEAt5Zw17UTNDnDGmZQKR0fqLpWy 786Lm5OScb7DjEgcA2PRm17st4UQ1kF0rQHokVaotxRM74PPDB8bCsunlghJl1DRK9s1aSuN hL1Pv9VD8b4dFNvCo7b4hfAANPU67W40AaaGZ3UAfmw+1MYyo4QuAZGKzaP2ukbdCD/DYnqi tJy88XqWtyb4UQWKNoQqGKzlYXdKsldYqrLHGoMvj1UN9XcRtXHST/IaLn72o7j7/h/Ac5EL 8lSUVIG4TYn59NyxxAXa07Wi6zjVL1U11fTnFmE29ALYQEXKBI3KUO1A3p4sQWzU7uRmbuxn naUmm8RbpMcOfa9JjlXCLmQ5IP7Rr5tYZUCkZz08LIfF8UMXwH7OOEX87Y++EkAB+pzKZNNd hwoXulTAgjSy+OiaLtuCys9VdXLZ3Zy314azaCU3BoWgaMV0eAW/+gprWMXQM1lrlzvwlD/k whyy9wGf0AEPpLssLVt9VVxNjo6BIkt6d1pMg6mHsUEVzsFNBFVDXDQBEADNkrQYSREUL4D3 Gws46JEoZ9HEQOKtkrwjrzlw/tCmqVzERRPvz2Xg8n7+HRCrgqnodIYoUh5WsU84N03KlLue MNsWLJBvBaubYN4JuJIdRr4dS4oyF1/fQAQPHh8Thpiz0SAZFx6iWKB7Qrz3OrGCjTPcW6ei OMheesVS5hxietSmlin+SilmIAPZHx7n242u6kdHOh+/SyLImKn/dh9RzatVpUKbv34eP1wA GldWsRxbf3WP9pFNObSzI/Bo3kA89Xx2rO2roC+Gq4LeHvo7ptzcLcrqaHUAcZ3CgFG88CnA 6z6lBZn0WyewEcPOPdcUB2Q7D/NiUY+HDiV99rAYPJztjeTrBSTnHeSBPb+qn5ZZGQwIdUW9 YegxWKvXXHTwB5eMzo/RB6vffwqcnHDoe0q7VgzRRZJwpi6aMIXLfeWZ5Wrwaw2zldFuO4Dt 91pFzBSOIpeMtfgb/Pfe/a1WJ/GgaIRIBE+NUqckM+3zJHGmVPqJP/h2Iwv6nw8U+7Yyl6gU BLHFTg2hYnLFJI4Xjg+AX1hHFVKmvl3VBHIsBv0oDcsQWXqY+NaFahT0lRPjYtrTa1v3tem/ JoFzZ4B0p27K+qQCF2R96hVvuEyjzBmdq2esyE6zIqftdo4MOJho8uctOiWbwNNq2U9pPWmu 4vXVFBYIGmpyNPYzRm0QPwARAQABwsF8BBgBCgAmAhsMFiEEm9B+DgxR+NWWd7dUG5NDfTtB YpsFAmgXUF8FCRaWWyoACgkQG5NDfTtBYptO0w//dlXJs5/42hAXKsk+PDg3wyEFb4NpyA1v qmx7SfAzk9Hf6lWwU1O6AbqNMbh6PjEwadKUk1m04S7EjdQLsj/MBSgoQtCT3MDmWUUtHZd5 RYIPnPq3WVB47GtuO6/u375tsxhtf7vt95QSYJwCB+ZUgo4T+FV4hquZ4AsRkbgavtIzQisg Dgv76tnEv3YHV8Jn9mi/Bu0FURF+5kpdMfgo1sq6RXNQ//TVf8yFgRtTUdXxW/qHjlYURrm2 H4kutobVEIxiyu6m05q3e9eZB/TaMMNVORx+1kM3j7f0rwtEYUFzY1ygQfpcMDPl7pRYoJjB dSsm0ZuzDaCwaxg2t8hqQJBzJCezTOIkjHUsWAK+tEbU4Z4SnNpCyM3fBqsgYdJxjyC/tWVT AQ18NRLtPw7tK1rdcwCl0GFQHwSwk5pDpz1NH40e6lU+NcXSeiqkDDRkHlftKPV/dV+lQXiu jWt87ecuHlpL3uuQ0ZZNWqHgZoQLXoqC2ZV5KrtKWb/jyiFX/sxSrodALf0zf+tfHv0FZWT2 zHjUqd0t4njD/UOsuIMOQn4Ig0SdivYPfZukb5cdasKJukG1NOpbW7yRNivaCnfZz6dTawXw XRIV/KDsHQiyVxKvN73bThKhONkcX2LWuD928tAR6XMM2G5ovxLe09vuOzzfTWQDsm++9UKF a/A= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 15/08/2025 09:07, Yi xin Zhu wrote: > Hi Krzysztof, > > On 08/08/2025 14:10, Krzysztof wrote: >> >> >> Where is the changelog? >> > Sorry for missing the changelog. I will include it in V3 patch. > >>> + intel,dma-sw-desc: >>> + type: boolean >>> + description: >>> + Indicates that the DMA driver should operate in >>> + software-managed >> mode. >>> + If this property is not present, it implies that DMA >>> + descriptors are >> managed and generated by another hardware component that controls the >> DMA engine. >> >> Nothing improved: >> 1. Still wrongly wrapped. >> 2. Still SW property. >> >> I don't think you read the feedback. You need to describe hardware, not SW. >> >> Best regards, >> Krzysztof > > Could you please give me some advice with regarding to the device tree attribute? > My understanding is if I can create a phandle link to describe the DMA descriptors are provided by some HW component. > That follows the comments. Something like this: > > intel,dma-desc-provider = <&xxx_hw>; > > Then it describes some HW component manages the DMA descriptors. It is not sufficient to tell. Creating phandles representing fake hardware is still not hardware description. > Without it, it means SW manage the DMA descriptors. > Please correct me if my understanding is wrong. Yes, it is wrong, because you focus on syntax instead of on the hardware problem or hardware characteristic. > > However, in the existing driver, HW manages descriptor mode is the default mode. > I can't create such link in the device tree without breaking the devicetree ABI. > So, is it okay I create an attribute like below ? > > Intel,dma-desc-provider = "CPU"; // it means CPU manage DMA descriptors. > > Intel,dma-desc-provider = "XXX_HW"; // it means XX_HW manage DMA descriptors. And how is it not a OS policy? Bring reasoning and arguments, otherwise I cannot help you. Your reply above has zero hardware-related arguments, zero facts, zero hardware description. Best regards, Krzysztof