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Fri, 9 Oct 2026 19:05:42 +0000 Date: Fri, 9 Oct 2026 14:05:38 -0500 From: Frank Li To: Vinod Koul Cc: dmaengine@vger.kernel.org, Frank Li , Wolfram Sang , Koichiro Den Subject: Re: [PATCH] docs: dmaengine: clarify ordering rules around cookie completion Message-ID: References: <20261009093745.539924-1-vkoul@kernel.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261009093745.539924-1-vkoul@kernel.org> X-ClientProxiedBy: FR0P281CA0053.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:48::17) To GV2PR04MB11799.eurprd04.prod.outlook.com (2603:10a6:150:2cf::9) Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: GV2PR04MB11799:EE_|DU4PR04MB11907:EE_ X-MS-Office365-Filtering-Correlation-Id: 6aadbb28-5e8d-4472-6dfb-08df2638509f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|366016|19092799006|23010399003|6133799003|18002099003|22082099003|10067099003|5023799004|11063799006|56012099006; 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It is good to > Document that for ensuring that dma buffer is flushed and no stale data > is seeing by consumer, we need to make sure such action is taken before > drivers invoke dma cookie completion. > > [1]: https://lore.kernel.org/r/20260917072507.5BDB61F000FF@smtp.kernel.org > > Signed-off-by: Vinod Koul > --- > Documentation/driver-api/dmaengine/provider.rst | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst > index 2897ade67b39..1bcbce705659 100644 > --- a/Documentation/driver-api/dmaengine/provider.rst > +++ b/Documentation/driver-api/dmaengine/provider.rst > @@ -557,6 +557,11 @@ dma_cookie_t > - Not really relevant any more since the introduction of ``virt-dma`` > that abstracts it away. > > +- dmaengine drivers need to ensure buffers are flushed before invoking > + vchan_cookie_complete() or dma_cookie_complete(). This would imply a call > + to unmapping buffers or any such architcure calls to ensure caller seeing Sashiko report a typo architcure Reviewed-by: Frank Li > + buffers are flushed is done before invoking these calls. > + > dma_vec > > - A small structure that contains a DMA address and length. > -- > 2.53.0 >