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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D9D32C64EAD for ; Tue, 9 Oct 2018 10:05:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 915E52075C for ; Tue, 9 Oct 2018 10:05:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 915E52075C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726678AbeJIRVo (ORCPT ); Tue, 9 Oct 2018 13:21:44 -0400 Received: from mail.bootlin.com ([62.4.15.54]:46161 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725892AbeJIRVo (ORCPT ); Tue, 9 Oct 2018 13:21:44 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 8EF782075C; Tue, 9 Oct 2018 12:05:32 +0200 (CEST) Received: from bbrezillon (AAubervilliers-681-1-28-153.w90-88.abo.wanadoo.fr [90.88.148.153]) by mail.bootlin.com (Postfix) with ESMTPSA id 4F50220717; Tue, 9 Oct 2018 12:05:22 +0200 (CEST) Date: Tue, 9 Oct 2018 12:05:22 +0200 From: Boris Brezillon To: Chuanhua Han Cc: "broonie@kernel.org" , "linux-spi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "eha@deif.com" Subject: Re: [PATCH 1/2] spi: spi-mem: Add the spi_set_xfer_bpw function Message-ID: <20181009120522.6b2bd15a@bbrezillon> In-Reply-To: References: <20180921070628.35153-1-chuanhua.han@nxp.com> <20180928084431.300b7bf9@bbrezillon> <20180928091833.15e95f7f@bbrezillon> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Oct 2018 09:52:23 +0000 Chuanhua Han wrote: > 1. In the dspi driver (spi controller), bits_per_word > (dspi->bits_per_word = transfer->bits_per_word) passed from the upper > layer (spi-mem.c) is used. In this way, I can only assign the > appropriate value of transfer->bits_per_word before passing to the > controller, that is, the controller driver does not know the value of > bits_per_word, and it will use this value when the upper level sets > what value is passed. I think you're missing my point: ->bits_per_word is not what you're looking for if what you're trying to do is use 32-bits accesses when things are properly aligned. > 2. As I understand, bits_per_word does not > exist for non-byte alignment, but for the need to reserve non-byte > transmission mode that meets the controller. Exactly. It's an optimization you have to take care of inside your driver. The core cannot help you with that. > 3. In addition, now the > XSPI of dspi cannot transfer data normally, so this problem needs to > be solved. I still don't understand what the problem is. > As for the DMA transfer mode, some colleagues will study > it.