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Message-ID: <20160813003703.4e86c042@bbrezillon>
Date: Sat, 13 Aug 2016 00:37:03 +0200
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Kyle Roeschley <kyle.roeschley@...com>
Cc: richard@....at, dwmw2@...radead.org, computersforpeace@...il.com,
beanhuo@...ron.com, linux-mtd@...ts.infradead.org,
linux-kernel@...r.kernel.org, nathan.sullivan@...com,
xander.huff@...com, peterpansjtu@...il.com
Subject: Re: [PATCH v7 1/2] mtd: nand_bbt: Move BBT block selection logic
out of write_bbt()
On Fri, 12 Aug 2016 16:58:22 -0500
Kyle Roeschley <kyle.roeschley@...com> wrote:
> From: Boris Brezillon <boris.brezillon@...e-electrons.com>
>
> This clarifies the write_bbt() by removing the write label and
> clarifying the error/exit path.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> Tested-by: Kyle Roeschley <kyle.roeschley@...com>
> ---
> v7: Move all code cleanup into first patch
> Correct documentation of mark_bbt_block_bad
> Make pr_warn messages consistent
> Add Tested-bys
>
> v6: Split functionality of write_bbt out into new functions
>
> v5: De-duplicate bad block handling
>
> v4: Don't ignore write protection while marking bad BBT blocks
> Correctly call block_markbad
> Minor cleanups
>
> v3: Don't overload mtd->priv
> Keep nand_erase_nand from erroring on protected BBT blocks
>
> v2: Mark OOB area in each block as well as BBT
> Avoid marking read-only, bad address, or known bad blocks as bad
>
> drivers/mtd/nand/nand_bbt.c | 114 +++++++++++++++++++++++++++++---------------
> 1 file changed, 76 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
> index 2fbb523..918db24 100644
> --- a/drivers/mtd/nand/nand_bbt.c
> +++ b/drivers/mtd/nand/nand_bbt.c
> @@ -605,6 +605,69 @@ static void search_read_bbts(struct mtd_info *mtd, uint8_t *buf,
> }
>
> /**
> + * get_bbt_block - Get the first valid eraseblock suitable to store a BBT
> + * @this: the NAND device
> + * @td: the BBT description
> + * @md: the mirror BBT descriptor
> + * @chip: the CHIP selector
> + *
> + * This functions returns a positive block number pointing a valid eraseblock
> + * suitable to store a BBT (i.e. in the range reserved for BBT), or -ENOSPC if
> + * all blocks are already used of marked bad. If td->pages[chip] was already
> + * pointing to a valid block we re-use it, otherwise we search for the next
> + * valid one.
> + */
> +static int get_bbt_block(struct nand_chip *this, struct nand_bbt_descr *td,
> + struct nand_bbt_descr *md, int chip)
> +{
> + int startblock, dir, page, numblocks, i;
> +
> + /*
> + * There was already a version of the table, reuse the page. This
> + * applies for absolute placement too, as we have the page number in
> + * td->pages.
> + */
> + if (td->pages[chip] != -1)
> + return td->pages[chip] >>
> + (this->bbt_erase_shift - this->page_shift);
> +
> + numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
> + if (!(td->options & NAND_BBT_PERCHIP))
> + numblocks *= this->numchips;
> +
> + /*
> + * Automatic placement of the bad block table. Search direction
> + * top -> down?
> + */
> + if (td->options & NAND_BBT_LASTBLOCK) {
> + startblock = numblocks * (chip + 1) - 1;
> + dir = -1;
> + } else {
> + startblock = chip * numblocks;
> + dir = 1;
> + }
> +
> + for (i = 0; i < td->maxblocks; i++) {
> + int block = startblock + dir * i;
> +
> + /* Check, if the block is bad */
> + switch (bbt_get_entry(this, block)) {
> + case BBT_BLOCK_WORN:
> + case BBT_BLOCK_FACTORY_BAD:
> + continue;
> + }
> +
> + page = block << (this->bbt_erase_shift - this->page_shift);
> +
> + /* Check, if the block is used by the mirror table */
> + if (!md || md->pages[chip] != page)
> + return block;
> + }
> +
> + return -ENOSPC;
> +}
> +
> +/**
> * write_bbt - [GENERIC] (Re)write the bad block table
> * @mtd: MTD device structure
> * @buf: temporary buffer
> @@ -621,7 +684,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
> struct nand_chip *this = mtd_to_nand(mtd);
> struct erase_info einfo;
> int i, res, chip = 0;
> - int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
> + int bits, page, offs, numblocks, sft, sftmsk;
> int nrchips, pageoffs, ooboffs;
> uint8_t msk[4];
> uint8_t rcode = td->reserved_block_code;
> @@ -652,46 +715,21 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
> }
>
> /* Loop through the chips */
> - for (; chip < nrchips; chip++) {
> - /*
> - * There was already a version of the table, reuse the page
> - * This applies for absolute placement too, as we have the
> - * page nr. in td->pages.
> - */
> - if (td->pages[chip] != -1) {
> - page = td->pages[chip];
> - goto write;
> + while (chip < nrchips) {
I'm probably missing something, but why are you turning the for loop
into a while loop in this patch? The commit message does not mention
that, and I don't see why you need it before you actually start
reworking the code to recover from BBT write failures (which is done in
patch 2).
> + int block;
> +
> + block = get_bbt_block(this, td, md, chip);
> + if (block < 0) {
> + pr_err("No space left to write bad block table\n");
> + res = block;
> + goto outerr;
> }
>
> /*
> - * Automatic placement of the bad block table. Search direction
> - * top -> down?
> + * get_bbt_block() returns a block number, shift the value to
> + * get a page number.
> */
> - if (td->options & NAND_BBT_LASTBLOCK) {
> - startblock = numblocks * (chip + 1) - 1;
> - dir = -1;
> - } else {
> - startblock = chip * numblocks;
> - dir = 1;
> - }
> -
> - for (i = 0; i < td->maxblocks; i++) {
> - int block = startblock + dir * i;
> - /* Check, if the block is bad */
> - switch (bbt_get_entry(this, block)) {
> - case BBT_BLOCK_WORN:
> - case BBT_BLOCK_FACTORY_BAD:
> - continue;
> - }
> - page = block <<
> - (this->bbt_erase_shift - this->page_shift);
> - /* Check, if the block is used by the mirror table */
> - if (!md || md->pages[chip] != page)
> - goto write;
> - }
> - pr_err("No space left to write bad block table\n");
> - return -ENOSPC;
> - write:
> + page = block << (this->bbt_erase_shift - this->page_shift);
>
> /* Set up shift count and masks for the flash table */
> bits = td->options & NAND_BBT_NRBITS_MSK;
> @@ -800,7 +838,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
> (unsigned long long)to, td->version[chip]);
>
> /* Mark it as used */
> - td->pages[chip] = page;
> + td->pages[chip++] = page;
> }
> return 0;
>
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