From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752844AbeDQLoB (ORCPT ); Tue, 17 Apr 2018 07:44:01 -0400 Received: from mail-by2nam01on0047.outbound.protection.outlook.com ([104.47.34.47]:47349 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752332AbeDQLn7 (ORCPT ); Tue, 17 Apr 2018 07:43:59 -0400 From: Radhey Shyam Pandey To: Vinod Koul CC: "dan.j.williams@intel.com" , "michal.simek@xilinx.com" , "Appana Durga Kedareswara Rao" , "lars@metafoo.de" , "dmaengine@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: RE: [RFC 2/6] dmaengine: xilinx_dma: Pass AXI4-Stream control words to netdev dma client Thread-Topic: [RFC 2/6] dmaengine: xilinx_dma: Pass AXI4-Stream control words to netdev dma client Thread-Index: AQHTym7m2V209m7Mdku6MMzd169mt6P7VJGAgAmMXFA= Date: Tue, 17 Apr 2018 11:43:56 +0000 Message-ID: References: <1522665546-10035-1-git-send-email-radheys@xilinx.com> <1522665546-10035-3-git-send-email-radheys@xilinx.com> <20180411090854.GY6014@localhost> In-Reply-To: <20180411090854.GY6014@localhost> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply X-MS-TNEF-Correlator: x-originating-ip: [182.72.145.30] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;BN6PR02MB2291;7:7tjXP6lVB61pZMaYzMoDTKWODvxlpdiswxEkcSlbfouVuFJ99FeMmtCt2MS9DAIlx4K3onqiqYoaaHBHqTcAg76+MqVDDqfXbr8QDnHQFi9xqoOmKyzEMlbQiX4ZnTTxVXi5RJ3pyiTP8TKLynpa3lF5TLVALn74ZfuqY80+zUEtNRcwE5S3eXDE9j4ung+MA/+s/sS/pXX6tXRDQjXSSFfXa/IGDPVPFH6q0vl61pnoIl6aIIARVl9PLSHhbBl2 x-ms-exchange-antispam-srfa-diagnostics: SOS;SOR; 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michal.simek@xilinx.com; Appana Durga > Kedareswara Rao ; Radhey Shyam Pandey > ; lars@metafoo.de; dmaengine@vger.kernel.org; > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org > Subject: Re: [RFC 2/6] dmaengine: xilinx_dma: Pass AXI4-Stream control > words to netdev dma client > > On Mon, Apr 02, 2018 at 04:09:02PM +0530, Radhey Shyam Pandey wrote: > > > + > > + if (chan->xdev->has_axieth_connected) { > > + seg = list_first_entry(&desc->segments, > > + struct xilinx_axidma_tx_segment, > node); > > + if (cb.callback_param) { > > + app_w = (u32 *) cb.callback_param; > > why are you interpreting callback_param? This is plainly wrong. > we do not know what is the interpretation of callback_param and it is > internal to submitter. In design, if AXI DMA is connected to AXI Ethernet IP there are certain AXI4-Stream Status fields (RX) that we need to pass to ethernet driver along with data buffer. An example includes: checksum fields, packet length etc. To pass these control words there is a structure defined between dmaengine and client. Before calling the client callback stream control words are copied to dma client callback_param struct (only if axieth is connected). I understand it's not an ideal way and we shouldn't be interpreting callback_param but couldn't find any better alternative of passing custom information from dmaengine to client driver and still be aligned to the framework. > > What exactly is the problem you are trying to solve? As mentioned above we need to pass AXI4-stream words(custom data) from dmaengine driver to dma client driver(ethernet) for each DMA descriptor. Current solution populates callback_param struct (only if axieth is connected). Please let me know if there is an alternate solution. > > > + hw = &seg->hw; > > + *app_w = hw->status & > XILINX_DMA_MAX_TRANS_LEN; > > + memcpy(app_w, hw->app, sizeof(u32) * > > + XILINX_DMA_NUM_APP_WORDS); > > + } > > -- > ~Vinod