Messages in this thread Patch in this message | | | Date | Mon, 9 Jun 2008 13:31:24 +0200 | From | Haavard Skinnemoen <> | Subject | Re: [patch 2.6.26-rc5-git] at91_nand speedup via {read,write}s{b,w}() |
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David Brownell <david-b@pacbell.net> 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 <dbrownell@users.sourceforge.net> > --- > 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 <david-b@pacbell.net> 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 <dbrownell@users.sourceforge.net> [haavard.skinnemoen@atmel.com: rebase onto atmel_nand rename] Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> --- 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
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