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Date: Mon, 3 Oct 2011 00:20:06 +0200
From: Sebastian Rasmussen <sebras@...il.com>
To: Namjae Jeon <linkinjeon@...il.com>
Cc: cjb@...top.org, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org, awarkentin@...are.com,
adrian.hunter@...el.com, linus.walleij@...aro.org,
james_p_freyensee@...ux.intel.com, Ulf.Hansson@...ricsson.com,
stefan.xk.nilsson@...ricsson.com, per.forlin@...ricsson.com,
johan.rudholm@...ricsson.com
Subject: Re: [PATCH v7] mmc : general purpose partition support.
Hi!
> It allows gerneral purpose partitions in MMC Device.
Reading this patch raised a few questions with me. I hope
you can find some time to answer some of them.
> And I try to simpliy make mmc_blk_alloc_parts using mmc_part structure suggested by Andrei Warkentin.
> After patching, we can see general purpose partitions like this.
>> cat /proc/partitions
> 179 0 847872 mmcblk0
> 179 192 4096 mmcblk0gp3
> 179 160 4096 mmcblk0gp2
> 179 128 4096 mmcblk0gp1
> 179 96 1052672 mmcblk0gp0
> 179 64 1024 mmcblk0boot1
> 179 32 1024 mmcblk0boot0
>
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
> ---
> drivers/mmc/card/block.c | 31 +++++++++++++++++--------------
> drivers/mmc/core/mmc.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
> include/linux/mmc/card.h | 33 ++++++++++++++++++++++++++++++++-
> include/linux/mmc/mmc.h | 2 +-
> 4 files changed, 93 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 1ff5486..56f7185 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1377,26 +1377,29 @@ static int mmc_blk_alloc_part(struct mmc_card *card,
> return 0;
> }
>
> +/* MMC Physical partition consist of two boot partitons and
> + * four general purpose partitions.
up to four general purpose partitions.
> + * if the register of respective partitions is set in ext_csd,
> + * it allocate block device to be accessed.
For each partition enabled in EXT_CSD a block device will
be allocated to provide access to the partition.
> + */
> +
> static int mmc_blk_alloc_parts(struct mmc_card *card, struct mmc_blk_data *md)
> {
> - int ret = 0;
> + int idx, ret = 0;
>
> if (!mmc_card_mmc(card))
> return 0;
>
> - if (card->ext_csd.boot_size) {
> - ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT0,
> - card->ext_csd.boot_size >> 9,
> - true,
> - "boot0");
> - if (ret)
> - return ret;
> - ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT1,
> - card->ext_csd.boot_size >> 9,
> - true,
> - "boot1");
> - if (ret)
> - return ret;
> + for (idx = 0; idx < card->nr_parts; idx++) {
> + if (card->part[idx].size) {
> + ret = mmc_blk_alloc_part(card, md,
> + card->part[idx].cookie,
> + card->part[idx].size >> 9,
> + card->part[idx].force_ro,
> + card->part[idx].name);
> + if (ret)
> + return ret;
> + }
> }
>
> return ret;
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 5700b1c..818778f 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -239,7 +239,8 @@ static int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd)
> */
> static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
> {
> - int err = 0;
> + int err = 0, idx;
> + unsigned int part_size, gp_size_mult;
>
> BUG_ON(!card);
>
> @@ -340,7 +341,15 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
> * There are two boot regions of equal size, defined in
> * multiples of 128K.
> */
> - card->ext_csd.boot_size = ext_csd[EXT_CSD_BOOT_MULT] << 17;
> + if (ext_csd[EXT_CSD_BOOT_MULT]) {
> + for (idx = 0; idx < MMC_NUM_BOOT_PARTITION;
> + idx++) {
> + part_size = ext_csd[EXT_CSD_BOOT_MULT] << 17;
> + mmc_part_add(card, part_size,
> + EXT_CSD_PART_CONFIG_ACC_BOOT0 + idx,
> + "boot%d", idx, true);
> + }
> + }
> }
>
> card->ext_csd.raw_hc_erase_gap_size =
> @@ -392,6 +401,38 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
> card->ext_csd.enhanced_area_offset = -EINVAL;
> card->ext_csd.enhanced_area_size = -EINVAL;
> }
> +
> + /*
> + * General purpose partition feature support --
> + * If ext_csd have the size of general purpose partitions,
> + * set size, part_type, partition name in mmc_part.
What does part_type refer to?
> + */
> +
> + if (ext_csd[EXT_CSD_PARTITION_SUPPORT] & 0x1) {
Maybe #define PARTITIONING_EN (0x1) in mmc.h somewhere?
> + u8 hc_erase_grp_sz =
> + ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE];
> + u8 hc_wp_grp_sz =
> + ext_csd[EXT_CSD_HC_WP_GRP_SIZE];
> +
> + card->ext_csd.enhanced_area_en = 1;
Why is it ok to unconditionally enable this without checking
ext_csd[EXT_CSD_PARTITION_SUPPORT] & 0x02, i.e.
ENH_ATTRIBUTE_EN?
> +
> + for (idx = 0, gp_size_mult = 143;
> + idx < MMC_NUM_GP_PARTITION;
> + idx++, gp_size_mult += 3) {
> + if (!ext_csd[gp_size_mult] &&
> + !ext_csd[gp_size_mult + 1] &&
> + !ext_csd[gp_size_mult + 2])
> + continue;
> + part_size = (ext_csd[gp_size_mult + 2] << 16) +
> + (ext_csd[gp_size_mult + 1] << 8) +
> + ext_csd[gp_size_mult];
> + part_size *= (size_t)(hc_erase_grp_sz *
> + hc_wp_grp_sz);
> + mmc_part_add(card, part_size <<= 19,
Is <<= really a valid operator? Does this even compile?
> + EXT_CSD_PART_CONFIG_ACC_GP0 + idx,
> + "gp%d", idx, false);
> + }
I think the gp_size_mult being set to 143 is a magic number
not very well explained. Also I'm of the opinion that the code
above could be improved upon readability-wise. Below you
find my suggestion. This would loose the gp_size_mult variable
and instead depend on a proper constant that should go in mmc.h.
Mind you I haven't compiled or tested the code below.
#define EXT_CSD_GP_SIZE_MULT_X_Y 143 /* R/W */
for (idx = 0; idx < MMC_NUM_GP_PARTITION; idx++)
{
part_size =
(ext_csd[EXT_CSD_GP_SIZE_MULT_X_Y + idx * 3 + 2] << 16) |
(ext_csd[EXT_CSD_GP_SIZE_MULT_X_Y + idx * 3 + 1] << 8) |
(ext_csd[EXT_CSD_GP_SIZE_MULT_X_Y + idx * 3] << 0);
part_size *= (size_t)(hc_erase_grp_sz * hc_wp_grp_sz);
if (part_size)
mmc_part_add(card, part_size << 19,
EXT_CSD_PART_CONFIG_ACC_GP0 + idx,
"gp%d", idx, false);
}
> + }
> card->ext_csd.sec_trim_mult =
> ext_csd[EXT_CSD_SEC_TRIM_MULT];
> card->ext_csd.sec_erase_mult =
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index b460fc2..550c2ed 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -12,6 +12,7 @@
>
> #include <linux/mmc/core.h>
> #include <linux/mod_devicetable.h>
> +#include <linux/genhd.h>
>
> struct mmc_cid {
> unsigned int manfid;
> @@ -63,7 +64,6 @@ struct mmc_ext_csd {
> bool enhanced_area_en; /* enable bit */
> unsigned long long enhanced_area_offset; /* Units: Byte */
> unsigned int enhanced_area_size; /* Units: KB */
> - unsigned int boot_size; /* in bytes */
> u8 raw_partition_support; /* 160 */
> u8 raw_erased_mem_count; /* 181 */
> u8 raw_ext_csd_structure; /* 194 */
> @@ -157,6 +157,22 @@ struct sdio_func_tuple;
>
> #define SDIO_MAX_FUNCS 7
>
> +/* The number of MMC physical partitions
> + * It consist of boot partitions(2), general purpose partitions(4) in MMC v4.4
> + */
> +#define MMC_NUM_BOOT_PARTITION 2
> +#define MMC_NUM_GP_PARTITION 4
Just to make the code above a little easier to fit into 80 characters,
maybe these should be known as MMC_BOOT_PARTS and
MMC_GENERAL_PARTS? That also expands the GP acronym
without making it too unwieldy.
> +
> +/*
> + * MMC Physical partitions
> + */
> +struct mmc_part {
> + unsigned int size; /* partition size (in bytes) */
> + unsigned int cookie; /* it used to part_type */
This information seems to be called part_type, cookie and
part_cfg in different parts of your patch. A common name
used everywhere is preferable, maybe settle on part_type?
> + char name[DISK_NAME_LEN];
> + bool force_ro; /* to make boot parts RO by default */
> +};
> +
> /*
> * MMC device
> */
> @@ -216,9 +232,24 @@ struct mmc_card {
> unsigned int sd_bus_speed; /* Bus Speed Mode set for the card */
>
> struct dentry *debugfs_root;
> + struct mmc_part part[MMC_NUM_BOOT_PARTITION + MMC_NUM_GP_PARTITION]; /* mmc physical partitions */
> + unsigned int nr_parts;
> };
>
> /*
> + * This function fill contents in mmc_part.
> + */
> +static inline void mmc_part_add(struct mmc_card *card, unsigned int size,
> + unsigned int part_cfg, char *name, int idx, bool ro)
> +{
> + card->part[card->nr_parts].size = size;
> + card->part[card->nr_parts].cookie = part_cfg;
> + sprintf(card->part[card->nr_parts].name, name, idx);
> + card->part[card->nr_parts].force_ro = ro;
> + card->nr_parts++;
> +}
> +
> +/*
> * The world is not perfect and supplies us with broken mmc/sdio devices.
> * For at least some of these bugs we need a work-around.
> */
> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
> index 5a794cb..29b7cb6 100644
> --- a/include/linux/mmc/mmc.h
> +++ b/include/linux/mmc/mmc.h
> @@ -302,7 +302,7 @@ struct _mmc_csd {
>
> #define EXT_CSD_PART_CONFIG_ACC_MASK (0x7)
> #define EXT_CSD_PART_CONFIG_ACC_BOOT0 (0x1)
> -#define EXT_CSD_PART_CONFIG_ACC_BOOT1 (0x2)
> +#define EXT_CSD_PART_CONFIG_ACC_GP0 (0x4)
>
> #define EXT_CSD_CMD_SET_NORMAL (1<<0)
> #define EXT_CSD_CMD_SET_SECURE (1<<1)
> --
> 1.7.4.4
>
>
/ Sebastian
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