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Re: [Qemu-devel] [PATCH] NAND: Correct random data reads.
From: |
andrzej zaborowski |
Subject: |
Re: [Qemu-devel] [PATCH] NAND: Correct random data reads. |
Date: |
Mon, 15 Dec 2008 03:31:55 +0100 |
2008/12/12 Edgar E. Iglesias <address@hidden>:
> I'm having problems with machine that uses a NAND_MFR_STMICRO 0xf1,
> recent Linux versions cannot properly read from the flash.
>
> Turns out that Linux MTD recently learned howto do randomly accessed reads
> from NAND flashes. QEMU has problemns emulating these.
>
> This patch fixes the problem for me but I've only tested on one flash
> model and only with Linux. I'd appreciate help with testing more machines
> with NANDs and ofcourse any comments people may have on the patch.
>
> Thanks
>
> commit 68a19f4348b12f85bd5fbfd8cf7b19033e1fd784
> Author: Edgar E. Iglesias <address@hidden>
> Date: Fri Dec 12 12:48:58 2008 +0100
>
> NAND: Correct random data reads.
>
> Random reading depends on having the last row/page latched and not beeing
> clobbered between read and any following random reads.
>
> Also, s->iolen must be updated when loading the io/data register with
> randomly
> accessed flash data.
>
> Signed-off-by: Edgar E. Iglesias <address@hidden>
>
> diff --git a/hw/nand.c b/hw/nand.c
> index 7c9f0aa..a6f67c6 100644
> --- a/hw/nand.c
> +++ b/hw/nand.c
> @@ -212,6 +212,7 @@ void nand_reset(struct nand_flash_s *s)
>
> static void nand_command(struct nand_flash_s *s)
> {
> + unsigned int offset;
> switch (s->cmd) {
> case NAND_CMD_READ0:
> s->iolen = 0;
> @@ -233,8 +234,12 @@ static void nand_command(struct nand_flash_s *s)
> case NAND_CMD_NOSERIALREAD2:
> if (!(nand_flash_ids[s->chip_id].options & NAND_SAMSUNG_LP))
> break;
> -
> - s->blk_load(s, s->addr, s->addr & ((1 << s->addr_shift) - 1));
> + offset = s->addr & ((1 << s->addr_shift) - 1);
> + s->blk_load(s, s->addr, offset);
> + if (s->gnd)
> + s->iolen = (1 << s->page_shift) - offset;
> + else
> + s->iolen = (1 << s->page_shift) + (1 << s->oob_shift) - offset;
> break;
>
> case NAND_CMD_RESET:
> @@ -380,12 +385,15 @@ void nand_setio(struct nand_flash_s *s, uint8_t value)
>
> if (s->cmd != NAND_CMD_RANDOMREAD2) {
> s->addrlen = 0;
> - s->addr = 0;
> }
> }
>
> if (s->ale) {
> - s->addr |= value << (s->addrlen * 8);
> + unsigned int shift = s->addrlen * 8;
> + unsigned int mask = ~(0xff << shift);
> + unsigned int v = value << shift;
> +
> + s->addr = (s->addr & mask) | v;
> s->addrlen ++;
>
> if (s->addrlen == 1 && s->cmd == NAND_CMD_READID)
> @@ -680,9 +688,6 @@ static void glue(nand_blk_load_, PAGE_SIZE)(struct
> nand_flash_s *s,
> offset, PAGE_SIZE + OOB_SIZE - offset);
> s->ioaddr = s->io;
> }
> -
> - s->addr &= PAGE_SIZE - 1;
> - s->addr += PAGE_SIZE;
Won't that break sequential reading? I think the other modifications
should also be conditional on the command being RANDOMREAD.
BTW, do you happen to know what the difference is between RANDOMREAD2
and NOSERIALREAD2? I basically added those commands because various
drivers I found had them declared or some specs had them but there
seems to be no standard or any place where they would be defined.
Cheers