From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11068C77B70 for ; Tue, 11 Apr 2023 14:46:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229515AbjDKOq6 (ORCPT ); Tue, 11 Apr 2023 10:46:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229960AbjDKOq5 (ORCPT ); Tue, 11 Apr 2023 10:46:57 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89750172A; Tue, 11 Apr 2023 07:46:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1681224416; x=1712760416; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=9YtPmGxmv4CA69+troKASVTIGrjtBdtTHpFIWMGP7kE=; b=X/a4SkGgOpz2KdNhcVuP26OLHFZeXrzbhdQCmf/N3/VH6y6TcxLvI6Xo G7NhZekGJEg46Q9bhfSpvto8pfdvi4yWaOpQ06yOz+yvSc5YCTPEDSKZG GgI6U90U/Hz9ns3YM1gYTCUebC0FbbTFwcTXhqEI4dWmzhude1XorHlbT Lcs4X1xECzsTM7YRlRdas7xuzL2nRjc0q/dAjZnZevTcFzcqnkgHp0RuT A56oLSGFncKOb+dmNtgOpEZwlXfJTG3t5eKV0FU+6a3nN7sHZCbcZ7/1Z ezk5mihRcKqqP50cG7KeT+cmvoCoDaoyR7Bh7iL2mhCI76zZNebR9imau g==; X-IronPort-AV: E=McAfee;i="6600,9927,10677"; a="327736711" X-IronPort-AV: E=Sophos;i="5.98,336,1673942400"; d="scan'208";a="327736711" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2023 07:46:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10677"; a="799945211" X-IronPort-AV: E=Sophos;i="5.98,336,1673942400"; d="scan'208";a="799945211" Received: from smile.fi.intel.com ([10.237.72.54]) by fmsmga002.fm.intel.com with ESMTP; 11 Apr 2023 07:46:36 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1pmFGU-00FKMS-2q; Tue, 11 Apr 2023 17:46:34 +0300 Date: Tue, 11 Apr 2023 17:46:34 +0300 From: Andy Shevchenko To: Serge Semin Cc: Joy Chakraborty , Mark Brown , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, manugautam@google.com, rohitner@google.com Subject: Re: [PATCH v5 1/2] spi: dw: Add 32 bpw support to DW DMA Controller Message-ID: References: <20230330063450.2289058-1-joychakr@google.com> <20230330063450.2289058-2-joychakr@google.com> <20230411141115.vrfd6sud66u6xeog@mobilestation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230411141115.vrfd6sud66u6xeog@mobilestation> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org On Tue, Apr 11, 2023 at 05:11:15PM +0300, Serge Semin wrote: > On Tue, Apr 11, 2023 at 03:13:49PM +0300, Andy Shevchenko wrote: > > On Thu, Mar 30, 2023 at 06:34:49AM +0000, Joy Chakraborty wrote: ... > > > - if (n_bytes == 1) > > > + switch (n_bytes) { > > > + case 1: > > > return DMA_SLAVE_BUSWIDTH_1_BYTE; > > > - else if (n_bytes == 2) > > > + case 2: > > > return DMA_SLAVE_BUSWIDTH_2_BYTES; > > > - > > > - return DMA_SLAVE_BUSWIDTH_UNDEFINED; > > > > > + case 3: > > > > I'm not sure about this. > > This actually makes sense seeing the function argument can have values > 1, 2, _3_ and 4: > dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE); > transfer->bits_per_word = __F__(master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32)); > ... > dw_spi_dma_convert_width(dws->n_bytes) > > The spi_transfer.bits_per_word field value depends on the > SPI peripheral device communication protocol requirements which may > imply the 3-bytes word xfers (even though it's indeed unluckily). > > This semantic will also match to what we currently have in the > IRQ-based SPI-transfer implementation (see dw_writer() and > dw_reader()). Nice, but we have DMA_SLAVE_BUSWIDTH_3_BYTES definition for that. Why we don't use it? > > > + case 4: > > > + return DMA_SLAVE_BUSWIDTH_4_BYTES; > > > + default: > > > + return DMA_SLAVE_BUSWIDTH_UNDEFINED; > > > + } -- With Best Regards, Andy Shevchenko