[PATCH 02/25] pxa3xx_nand: introduce common timing to reduce read id times
Eric Miao
eric.y.miao at gmail.com
Fri Jun 18 02:33:59 EDT 2010
On Fri, Jun 18, 2010 at 1:33 PM, Haojian Zhuang
<haojian.zhuang at gmail.com> wrote:
> From 832379d0da4d772e45872de365053f9a15733967 Mon Sep 17 00:00:00 2001
> From: Lei Wen <leiwen at marvell.com>
> Date: Wed, 2 Jun 2010 21:50:25 +0800
> Subject: [PATCH 02/25] pxa3xx_nand: introduce common timing to reduce
> read id times
>
> We certainly don't need to send read id command times by times, since
> we already know what the id is after the first read id...
>
> So create a common timing which could ensure it would successfully read id
> out all supported chip. Then follow the build-in table to reconfigure
> the timing.
This is clever trick we'd like to have. And I'd prefer to call this a
'loose timing'
or a 'default safe timing' instead of 'common timing'.
>
> Signed-off-by: Lei Wen <leiwen at marvell.com>
> Signed-off-by: Haojian Zhuang <haojian.zhuang at marvell.com>
> ---
> drivers/mtd/nand/pxa3xx_nand.c | 72 ++++++++++++++++-----------------------
> 1 files changed, 30 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
> index 013e075..f939083 100644
> --- a/drivers/mtd/nand/pxa3xx_nand.c
> +++ b/drivers/mtd/nand/pxa3xx_nand.c
> @@ -226,23 +226,26 @@ const static struct pxa3xx_nand_cmdset cmdset = {
> };
>
> static struct pxa3xx_nand_timing __devinitdata timing[] = {
> + /* common timing used to detect flash id */
> + { 40, 80, 60, 100, 80, 100, 90000, 400, 40, },
Make sure this is the loose and safe enough timing.
> /* Samsung NAND series */
> - { 10, 0, 20, 40, 30, 40, 11123, 110, 10, },
> + { 10, 0, 20, 40, 30, 40, 11123, 110, 10, },
> /* Micron NAND series */
> - { 10, 25, 15, 25, 15, 30, 25000, 60, 10, },
> + { 10, 25, 15, 25, 15, 30, 25000, 60, 10, },
> /* ST NAND series */
> - { 10, 35, 15, 25, 15, 25, 25000, 60, 10, },
> + { 10, 35, 15, 25, 15, 25, 25000, 60, 10, },
> };
>
> static struct pxa3xx_nand_flash __devinitdata builtin_flash_types[] = {
> - { 0x46ec, 32, 512, 16, 16, 4096, &timing[0], },
> - { 0xdaec, 64, 2048, 8, 8, 2048, &timing[0], },
> - { 0xd7ec, 128, 4096, 8, 8, 8192, &timing[0], },
> - { 0xa12c, 64, 2048, 8, 8, 1024, &timing[1], },
> - { 0xb12c, 64, 2048, 16, 16, 1024, &timing[1], },
> - { 0xdc2c, 64, 2048, 8, 8, 4096, &timing[1], },
> - { 0xcc2c, 64, 2048, 16, 16, 4096, &timing[1], },
> - { 0xba20, 64, 2048, 16, 16, 2048, &timing[2], },
> + { 0, 0, 0, 0, 0, 0, &timing[0], },
> + { 0x46ec, 32, 512, 16, 16, 4096, &timing[1], },
> + { 0xdaec, 64, 2048, 8, 8, 2048, &timing[1], },
> + { 0xd7ec, 128, 4096, 8, 8, 8192, &timing[1], },
> + { 0xa12c, 64, 2048, 8, 8, 1024, &timing[2], },
> + { 0xb12c, 64, 2048, 16, 16, 1024, &timing[2], },
> + { 0xdc2c, 64, 2048, 8, 8, 4096, &timing[2], },
> + { 0xcc2c, 64, 2048, 16, 16, 4096, &timing[2], },
> + { 0xba20, 64, 2048, 16, 16, 2048, &timing[3], },
> };
>
> #define NDTR0_tCH(c) (min((c), 7) << 19)
> @@ -859,12 +862,6 @@ static int pxa3xx_nand_config_flash(struct
> pxa3xx_nand_info *info,
> struct pxa3xx_nand_platform_data *pdata = pdev->dev.platform_data;
> uint32_t ndcr = 0x00000FFF; /* disable all interrupts */
>
> - if (f->page_size != 2048 && f->page_size != 512)
> - return -EINVAL;
> -
> - if (f->flash_width != 16 && f->flash_width != 8)
> - return -EINVAL;
> -
I do think these are sanity check, that's useful to prevent incorrectly defined
data (esp. coming from board code). Can we define the loose flash type as:
> static struct pxa3xx_nand_flash __devinitdata builtin_flash_types[] = {
> + { 0x0000, 0, 512, 8, 8, 0, &timing[0], },
> + { 0x46ec, 32, 512, 16, 16, 4096, &timing[1], },
> + { 0xdaec, 64, 2048, 8, 8, 2048, &timing[1], },
with a comment of /* default flash type to detect ID */?
My understanding is the minimum requirement to detect the NAND ID is a
loose timing and 512 small page, 8-bit wide bus, so with a chip_id being
0x0000, that should be enough to tell it's a special flash type to detect ID.
> /* calculate flash information */
> info->oob_size = (f->page_size == 2048) ? 64 : 16;
> info->read_id_bytes = (f->page_size == 2048) ? 4 : 2;
> @@ -976,36 +973,27 @@ static int pxa3xx_nand_detect_flash(struct
> pxa3xx_nand_info *info,
> if (pxa3xx_nand_detect_config(info) == 0)
> return 0;
>
> - for (i = 0; i<pdata->num_flash; ++i) {
> - f = pdata->flash + i;
> -
> - if (pxa3xx_nand_config_flash(info, f))
> - continue;
> -
> - if (__readid(info, &id))
> - continue;
> -
> - if (id == f->chip_id)
> - return 0;
> - }
> -
> - for (i = 0; i < ARRAY_SIZE(builtin_flash_types); i++) {
> -
> - f = &builtin_flash_types[i];
> -
> - if (pxa3xx_nand_config_flash(info, f))
> - continue;
> -
> - if (__readid(info, &id))
> - continue;
> -
> - if (id == f->chip_id)
> + f = &builtin_flash_types[0];
> + pxa3xx_nand_config_flash(info, f);
> + if (__readid(info, &id))
> + goto fail_detect;
> +
> + for (i=0; i<ARRAY_SIZE(builtin_flash_types) + pdata->num_flash - 1; i++) {
> + if (i < pdata->num_flash)
> + f = pdata->flash + i;
> + else
> + f = &builtin_flash_types[i - pdata->num_flash + 1];
This looks a bit tricky and difficult to read, can you improve the
readability here?
> + if (f->chip_id == id) {
> + dev_info(&info->pdev->dev, "detect chip id: 0x%x\n", id);
> + pxa3xx_nand_config_flash(info, f);
> return 0;
> + }
> }
>
> dev_warn(&info->pdev->dev,
> - "failed to detect configured nand flash; found %04x instead of\n",
> + "failed to detect configured nand flash; found %04x instead of\n",
> id);
> +fail_detect:
> return -ENODEV;
> }
>
I'm generally OK with the idea.
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