From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 AE66823D5 for ; Mon, 6 Nov 2023 08:44:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from fd01.gateway.ufhost.com (fd01.gateway.ufhost.com [61.152.239.71]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F039C9 for ; Mon, 6 Nov 2023 00:44:05 -0800 (PST) Received: from EXMBX166.cuchost.com (unknown [175.102.18.54]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "EXMBX166", Issuer "EXMBX166" (not verified)) by fd01.gateway.ufhost.com (Postfix) with ESMTP id 84C0C24E0D6; Mon, 6 Nov 2023 16:44:03 +0800 (CST) Received: from EXMBX066.cuchost.com (172.16.7.66) by EXMBX166.cuchost.com (172.16.6.76) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Mon, 6 Nov 2023 16:44:03 +0800 Received: from EXMBX061.cuchost.com (172.16.6.61) by EXMBX066.cuchost.com (172.16.6.66) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Mon, 6 Nov 2023 16:44:02 +0800 Received: from EXMBX061.cuchost.com ([fe80::b087:fbb:9f87:209e]) by EXMBX061.cuchost.com ([fe80::b087:fbb:9f87:209e%14]) with mapi id 15.00.1497.044; Mon, 6 Nov 2023 16:44:03 +0800 From: EnDe Tan To: Vinod Koul CC: "dmaengine@vger.kernel.org" , "Eugeniy.Paltsev@synopsys.com" Subject: RE: [v2,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst Thread-Topic: [v2,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst Thread-Index: AQHZ5jIa8o2rI4fa4EKYBk4YoIeto7A5OwMAgDQLZWA= Date: Mon, 6 Nov 2023 08:44:02 +0000 Message-ID: <5c6b1d6c73ff4b558457bf248a0d0bb0@EXMBX061.cuchost.com> References: <20230913110425.1271-1-ende.tan@starfivetech.com> In-Reply-To: Accept-Language: en-US, zh-CN Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [202.188.176.82] x-yovoleruleagent: yovoleflag Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 > Are client drivers setting this today, will there be regression if not se= t? I don't see any dw-axi-dmac client driver setting this src_maxburt/dst_maxb= urst explicitly. This means that all the while, those client drivers have been using the def= ault value of DWAXIDMAC_BURST_TRANS_LEN_4. In the patch, to maintain this backward compatibility, ternary operator is = used, for example: > > + dst_burst_trans_len =3D chan->config.dst_maxburst ? > > + __ffs(chan->config.dst_maxburst) - 1 : > > + DWAXIDMAC_BURST_TRANS_LEN_4; so that if src_maxburst/dst_maxburst is not set, default value of DWAXIDMAC= _BURST_TRANS_LEN_4 applies. > this is wrong, memcpy should never use slave config value. These values a= re > for peripheral and not meant for mem-mem transfers Agreed, thanks for pointing that out. It shall be removed in patch v3.