From patchwork Thu Jun 24 09:39:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amelie Delaunay X-Patchwork-Id: 12341665 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3788C49EAF for ; Thu, 24 Jun 2021 09:40:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8960B613F7 for ; Thu, 24 Jun 2021 09:40:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232021AbhFXJml (ORCPT ); Thu, 24 Jun 2021 05:42:41 -0400 Received: from mx07-00178001.pphosted.com ([185.132.182.106]:21674 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232005AbhFXJmk (ORCPT ); Thu, 24 Jun 2021 05:42:40 -0400 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 15O9c8Vv004857; Thu, 24 Jun 2021 11:40:04 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=selector1; bh=qEDhYt2leubu9mAEDVbUmPNoFRyqAPacUpoePznnKfA=; b=Nwm8bRawBzC/qpnqKlVQgFY7oKw+Tc9AdgynK8AFL9epY57FDo6yE4nLFSD+Ek9zzJF9 gNEZYSKBvFSLJu3GBp5PojyzPHHqWcbCcAVv7dns7RRucwUCsGPKM8kfWoCO5ZhWAkg2 Ro1AdyCWPIxXtBASmeXsHcOC3LewqZ4mkJYo8M5WhIz5kf6BMEYayyesSK2YpftAbHaM nijTAKl2n5IxeOf/T9MK9qAZOabJQFGFhNCq7NqsZq0+0HNj3z4BCLjyZ+ITgOA48SrM 1hk4qtiEqP2gKfv71NZmc+er+OMCZ5A9q+6DD5SNALirM0fJdn7MRnHr+M6Bw0SqgQXH 6w== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 39chf6jsvb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 24 Jun 2021 11:40:04 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 0A58810002A; Thu, 24 Jun 2021 11:40:04 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id E7F1D21B51B; Thu, 24 Jun 2021 11:40:03 +0200 (CEST) Received: from localhost (10.75.127.47) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 24 Jun 2021 11:40:03 +0200 From: Amelie Delaunay To: Vinod Koul , Rob Herring , Dan Williams , Maxime Coquelin , Alexandre Torgue CC: , , , , , Amelie Delaunay , Pierre-Yves Mordret Subject: [PATCH 1/2] dt-bindings: dma: add alternative REQ/ACK protocol selection in stm32-dma Date: Thu, 24 Jun 2021 11:39:58 +0200 Message-ID: <20210624093959.142265-2-amelie.delaunay@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210624093959.142265-1-amelie.delaunay@foss.st.com> References: <20210624093959.142265-1-amelie.delaunay@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.47] X-ClientProxiedBy: SFHDAG1NODE3.st.com (10.75.127.3) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-06-24_06:2021-06-24,2021-06-24 signatures=0 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Default REQ/ACK protocol consists in maintaining ACK signal up to the removal of REQuest and the transfer completion. In case of alternative REQ/ACK protocol, ACK de-assertion does not wait the removal of the REQuest, but only the transfer completion. Due to a possible DMA stream lock when transferring data to/from STM32 USART/UART, this new bindings allow to select this alternative protocol in device tree, especially for STM32 USART/UART nodes. Signed-off-by: Amelie Delaunay Acked-by: Rob Herring --- Documentation/devicetree/bindings/dma/st,stm32-dma.yaml | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml b/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml index 2a5325f480f6..4bf676fd25dc 100644 --- a/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml +++ b/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml @@ -40,6 +40,13 @@ description: | 0x0: FIFO mode with threshold selectable with bit 0-1 0x1: Direct mode: each DMA request immediately initiates a transfer from/to the memory, FIFO is bypassed. + -bit 4: alternative DMA request/acknowledge protocol + 0x0: Use standard DMA ACK management, where ACK signal is maintained + up to the removal of request and transfer completion + 0x1: Use alternative DMA ACK management, where ACK de-assertion does + not wait for the de-assertion of the REQuest, ACK is only managed + by transfer completion. This must only be used on channels + managing transfers for STM32 USART/UART. maintainers: