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 77771C0044C for ; Wed, 31 Oct 2018 13:43:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 34D7F2081B for ; Wed, 31 Oct 2018 13:43:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 34D7F2081B 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 S1729304AbeJaWl7 (ORCPT ); Wed, 31 Oct 2018 18:41:59 -0400 Received: from mail.bootlin.com ([62.4.15.54]:33628 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729118AbeJaWl6 (ORCPT ); Wed, 31 Oct 2018 18:41:58 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id B0CFB207CF; Wed, 31 Oct 2018 14:43:50 +0100 (CET) Received: from bbrezillon (aaubervilliers-681-1-12-210.w90-88.abo.wanadoo.fr [90.88.133.210]) by mail.bootlin.com (Postfix) with ESMTPSA id 3B14820756; Wed, 31 Oct 2018 14:43:40 +0100 (CET) Date: Wed, 31 Oct 2018 14:43:40 +0100 From: Boris Brezillon To: Piotr Bugalski Cc: Mark Brown , linux-spi@vger.kernel.org, David Woodhouse , Brian Norris , Marek Vasut , Richard Weinberger , linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring , Mark Rutland , Nicolas Ferre , Alexandre Belloni , Cyrille Pitchen , Tudor Ambarus Subject: Re: [RFC PATCH v2 0/6] New QuadSPI driver for Atmel SAMA5D2 Message-ID: <20181031144340.4f1a030a@bbrezillon> In-Reply-To: <20180627131609.13681-1-bugalski.piotr@gmail.com> References: <20180627131609.13681-1-bugalski.piotr@gmail.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; 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 Hi Piotr, Tudor, On Wed, 27 Jun 2018 15:16:03 +0200 Piotr Bugalski wrote: > Hello, > > Atmel SAMA5D2 is equipped with two QSPI interfaces. These interfaces can > work as in SPI-compatible mode or use two / four lines to improve > communication speed. At the moment there is QSPI driver strongly tied to > NOR-flash memory and MTD subsystem. > Intention of this change is to provide new driver which will not be tied > to MTD and allows using QSPI with NAND-flash memory or other peripherals > New spi-mem API provides abstraction layer which can disconnect QSPI > from MTD. This driver doesn't support regular SPI interface, it should > be used with spi-mem interface only. > Unfortunately SAMA5D2 hardware by default supports only NOR-flash > memory. It allows 24- and 32-bit addressing while NAND-flash requires > 16-bit long. To workaround hardware limitation driver is a bit more > complicated. > > Request to spi-mem contains three fiels: opcode (command), address, > dummy bytes. SAMA5D2 QSPI hardware supports opcode, address, dummy and > option byte where address field can only be 24- or 32- bytes long. > Handling 8-bits long addresses is done using option field. For 16-bits > address behaviour depends of number of requested dummy bits. If there > are 8 or more dummy cycles, address is shifted and sent with first dummy > byte. Otherwise opcode is disabled and first byte of address contains > command opcode (works only if opcode and address use the same buswidth). > The limitation is when 16-bit address is used without enough dummy > cycles and opcode is using different buswidth than address. Other modes > are supported with described workaround. > > It looks like hardware has some limitation in performance. The same issue > exists in current QSPI driver (MTD/nor-flash) and soft-pack (bare-metal > library from Atmel). Without using DMA read speed is much worse than > maximum bandwidth (efficiency 30-40%). Any help with performance > improvement is highly welcome, especially for NAND-flash memories which > offers higher capacity than NOR-flash used with previous driver. > > Best Regards, > Piotr > > v2 changes: > - driver is now replacement of existing atmel-quadspi > - code was re-written to follow original code structure > - deinitialization order fixed > - empty atmel_qspi_adjust_op_size function removed > - code formatting fixes > - use spi_device->max_speed_hz to get spi speed > - spi freqency set in spi_controller->setup() hook > - address range checkng for 4-bytes addressing > - use timeout to avoid infinite waiting IIRC, this version was almost ready to be merged except for the missing ->get_name() implementation which should be easy to add. Can one of you post a new version of this patchset? Thanks, Boris