Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760712AbYFILbA (ORCPT ); Mon, 9 Jun 2008 07:31:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759616AbYFILau (ORCPT ); Mon, 9 Jun 2008 07:30:50 -0400 Received: from smtpeu1.atmel.com ([195.65.72.27]:59817 "EHLO bagnes.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759596AbYFILat convert rfc822-to-8bit (ORCPT ); Mon, 9 Jun 2008 07:30:49 -0400 Date: Mon, 9 Jun 2008 13:31:24 +0200 From: Haavard Skinnemoen To: David Brownell Cc: lkml , linux-mtd@lists.infradead.org, Nicolas Ferre Subject: Re: [patch 2.6.26-rc5-git] at91_nand speedup via {read,write}s{b,w}() Message-ID: <20080609133124.0eb97e25@hskinnemo-gx745.norway.atmel.com> In-Reply-To: <200806090313.28515.david-b@pacbell.net> References: <200806090313.28515.david-b@pacbell.net> X-Mailer: Claws Mail 3.4.0 (GTK+ 2.12.9; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT X-OriginalArrivalTime: 09 Jun 2008 11:30:36.0971 (UTC) FILETIME=[3CEABFB0:01C8CA24] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6034 Lines: 181 David Brownell wrote: > This uses __raw_{read,write}s{b,w}() primitives to access data on NAND > chips for more efficient I/O. > > On an arm926 with memory clocked at 100 MHz, this reduced the elapsed > time for a 64 MByte read by 16%. ("dd" /dev/mtd0 to /dev/null, with > an 8-bit NAND using hardware ECC and 128KB blocksize.) Nice. Here are some numbers from my setup (256 MB, 8-bit, software ECC). Before: real 2m38.131s user 0m0.228s sys 2m37.740s After: real 2m27.404s user 0m0.180s sys 2m27.068s which is a 6.8% speedup. I guess hardware ECC helps...though I can't seem to get it to work properly. Is there anything I need to do besides flash_eraseall when changing the ECC layout? Also, I wonder if we can use the DMA engine framework to get rid of all that "sys" time...? > Also some minor section tweaks: > > - Use platform_driver_probe() so no pointer to probe() lingers > after that code has been removed at run-time. > > - Use __exit and __exit_p so the remove() code will normally be > removed by the linker. > > Since these buffer read/write calls are new, this increases the runtime > code footprint (by 88 bytes on my build, after the section tweaks). Yeah, I spotted a bug in __raw_readsb on avr32, so I guess those functions haven't actually been used before... > Signed-off-by: David Brownell > --- > Yeah, this does may you wonder why the *default* nand r/w code isn't > using these primitives; this speedup shouldn't be platform-specific. > > Posting this now since I think this should either be incorporated into > the new atmel_nand.c code or into drivers/mtd/nand/nand_base.c ... > both arm and avr32 support these calls, I'm not sure whether or not > some platforms don't support them. I'll leave it up to the MTD people to decide whether or not to update nand_base.c. Below is your patch rebased onto my patchset. I'll include it in my next series after I figure out where to send it. Haavard >From ad420ea11f9c8aa0fcad2ce1c3af69c02a2dc447 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Mon, 9 Jun 2008 03:13:28 -0700 Subject: [PATCH] atmel_nand speedup via {read,write}s{b,w}() This uses __raw_{read,write}s{b,w}() primitives to access data on NAND chips for more efficient I/O. On an arm926 with memory clocked at 100 MHz, this reduced the elapsed time for a 64 MByte read by 16%. ("dd" /dev/mtd0 to /dev/null, with an 8-bit NAND using hardware ECC and 128KB blocksize.) Also some minor section tweaks: - Use platform_driver_probe() so no pointer to probe() lingers after that code has been removed at run-time. - Use __exit and __exit_p so the remove() code will normally be removed by the linker. Since these buffer read/write calls are new, this increases the runtime code footprint (by 88 bytes on my build, after the section tweaks). Signed-off-by: David Brownell [haavard.skinnemoen@atmel.com: rebase onto atmel_nand rename] Signed-off-by: Haavard Skinnemoen --- drivers/mtd/nand/atmel_nand.c | 46 ++++++++++++++++++++++++++++++++++++---- 1 files changed, 41 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c index 325ce29..d9f7a5d 100644 --- a/drivers/mtd/nand/atmel_nand.c +++ b/drivers/mtd/nand/atmel_nand.c @@ -142,6 +142,37 @@ static int atmel_nand_device_ready(struct mtd_info *mtd) } /* + * Minimal-overhead PIO for data access. + */ +static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len) +{ + struct nand_chip *nand_chip = mtd->priv; + + __raw_readsb(nand_chip->IO_ADDR_R, buf, len); +} + +static void atmel_read_buf16(struct mtd_info *mtd, u8 *buf, int len) +{ + struct nand_chip *nand_chip = mtd->priv; + + __raw_readsw(nand_chip->IO_ADDR_R, buf, len / 2); +} + +static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len) +{ + struct nand_chip *nand_chip = mtd->priv; + + __raw_writesb(nand_chip->IO_ADDR_W, buf, len); +} + +static void atmel_write_buf16(struct mtd_info *mtd, const u8 *buf, int len) +{ + struct nand_chip *nand_chip = mtd->priv; + + __raw_writesw(nand_chip->IO_ADDR_W, buf, len / 2); +} + +/* * write oob for small pages */ static int atmel_nand_write_oob_512(struct mtd_info *mtd, @@ -436,8 +467,14 @@ static int __init atmel_nand_probe(struct platform_device *pdev) nand_chip->chip_delay = 20; /* 20us command delay time */ - if (host->board->bus_width_16) /* 16-bit bus width */ + if (host->board->bus_width_16) { /* 16-bit bus width */ nand_chip->options |= NAND_BUSWIDTH_16; + nand_chip->read_buf = atmel_read_buf16; + nand_chip->write_buf = atmel_write_buf16; + } else { + nand_chip->read_buf = atmel_read_buf; + nand_chip->write_buf = atmel_write_buf; + } platform_set_drvdata(pdev, host); atmel_nand_enable(host); @@ -546,7 +583,7 @@ err_nand_ioremap: /* * Remove a NAND device. */ -static int __devexit atmel_nand_remove(struct platform_device *pdev) +static int __exit atmel_nand_remove(struct platform_device *pdev) { struct atmel_nand_host *host = platform_get_drvdata(pdev); struct mtd_info *mtd = &host->mtd; @@ -564,8 +601,7 @@ static int __devexit atmel_nand_remove(struct platform_device *pdev) } static struct platform_driver atmel_nand_driver = { - .probe = atmel_nand_probe, - .remove = atmel_nand_remove, + .remove = __exit_p(atmel_nand_remove), .driver = { .name = "atmel_nand", .owner = THIS_MODULE, @@ -574,7 +610,7 @@ static struct platform_driver atmel_nand_driver = { static int __init atmel_nand_init(void) { - return platform_driver_register(&atmel_nand_driver); + return platform_driver_probe(&atmel_nand_driver, atmel_nand_probe); } -- 1.5.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/