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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CA0DFC5DF60 for ; Tue, 5 Nov 2019 16:04:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 93A48214B2 for ; Tue, 5 Nov 2019 16:04:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="bBQY6zSr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93A48214B2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=l997bPQIJElNs7RUM3665Vp6rsslKSBl9IO7LLkPMaY=; b=bBQY6zSrlU/3fexWvDy3TlR1p JD5WxSJtblPsVIrzpg/9x3Vc9AmEBDaN7s9cdQ5dXn7Lwjw9DTc9gLsu+y61BN3jpfqty7WwQCv2N qw1JbqjE+Z9iN/n/YIqo+kmsdiWHXYNdf0xlismGRlbiVWbUZ532CFgwBfh0GmHQa2Mlxf+bMYAjb jkeafEhYbNXh0rkrfbULsGEbMzgjD+EO+nUZcSEbKcmHfsnGAqLIWKfR1aFcLxZxRm610CHoUw6eR Myp+3BLE7lWhDZxTP3hgkmkdmgVfL/9PWWRZmL9IfBTaivmpPJ7nlfe9uXaS/C9gjqYUndxFwUh3Q GMfSBhGlw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iS1Jj-0003C9-In; Tue, 05 Nov 2019 16:04:27 +0000 Received: from lhrrgout.huawei.com ([185.176.76.210] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iS1Jf-00039b-U0 for linux-mtd@lists.infradead.org; Tue, 05 Nov 2019 16:04:25 +0000 Received: from LHREML711-CAH.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id B003DAE6B949189B4146; Tue, 5 Nov 2019 16:04:10 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by LHREML711-CAH.china.huawei.com (10.201.108.34) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 5 Nov 2019 16:04:10 +0000 Received: from [127.0.0.1] (10.202.226.46) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1713.5; Tue, 5 Nov 2019 16:04:09 +0000 Subject: Re: [PATCH 2/3] spi: Add HiSilicon v3xx SPI NOR flash controller driver To: Mark Brown References: <1572886297-45400-1-git-send-email-john.garry@huawei.com> <1572886297-45400-3-git-send-email-john.garry@huawei.com> <20191104192406.GH5238@sirena.co.uk> <855a67dc-1356-a763-e374-540f6ac400ab@huawei.com> <20191105110504.GA4500@sirena.co.uk> From: John Garry Message-ID: Date: Tue, 5 Nov 2019 16:04:09 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20191105110504.GA4500@sirena.co.uk> Content-Language: en-US X-Originating-IP: [10.202.226.46] X-ClientProxiedBy: lhreml703-chm.china.huawei.com (10.201.108.52) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191105_080424_116889_A5D315EE X-CRM114-Status: GOOD ( 12.93 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tudor.ambarus@microchip.com, linux-kernel@vger.kernel.org, linuxarm@huawei.com, linux-spi@vger.kernel.org, marek.vasut@gmail.com, linux-mtd@lists.infradead.org, xuejiancheng@hisilicon.com, fengsheng5@huawei.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On 05/11/2019 11:05, Mark Brown wrote: > On Tue, Nov 05, 2019 at 10:58:39AM +0000, John Garry wrote: >> On 04/11/2019 19:24, Mark Brown wrote: >>> On Tue, Nov 05, 2019 at 12:51:36AM +0800, John Garry wrote: > >>>> + if (len) { >>>> + u32 val; >>>> + >>>> + val = __raw_readl(host->regbase + CMD_DATABUF(words)); >>>> + >>>> + to += words * 4; >>>> + for (i = 0; i < len; i++, val >>= 8, to++) >>>> + *to = (u8)val; >>>> + } >>>> + } else { >>>> + for (i = 0; i < DIV_ROUND_UP(len, 4); i++) { >>>> + u32 val = __raw_readl(host->regbase + CMD_DATABUF(i)); >>>> + int j; > >>> The more usual pattern for these would be to do some unaligned accesses >>> for the start/end of the buffer to get to alignment and then transfer >>> the rest as aligned data. > >> Yeah, I understand you, but for that I would need to generate multiple >> transactions in the driver, and I wanted to keep 1x transaction per >> spi_controller_mem_ops.exec_op call. > Hi Mark, >> So maybe I can do some trickery in my adjust_op_size method to generate >> these multiple transactions: a. any unaligned start data b. the 32b-aligned >> data b. unaligned end. I think that the HW should be able to handle that. > > Right, that's what I was expecting. > So that should work for xfer data commands, but generally the read/write reg commands in the SPI NOR layer would not use spi_mem_adjust_op_size(), like spi-nor.c:spi_nor_read_id(), as an example. For these, I should be able to guarantee start alignment (since the buffer is kmalloc'ed), but not end alignment, so would still require 4-byte + single byte copies for these. Thanks, John ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/