On 2 February 2012 21:38, S, Venkatraman <svenkatr@xxxxxx> wrote:
> On Wed, Feb 1, 2012 at 8:57 PM, Saugata Das <saugata.das@xxxxxxxxxxxxxx> wrote:
>> From: Saugata Das <saugata.das@xxxxxxxxxx>
>>
>> This patch groups the read or write transfers to eMMC in different contexts
>> based on the block number. Transfers to consecutive blocks are grouped to a
>> common context. So several small transfers combine to give performance like
>> a large multi block transfer.
>>
>> The patch creates a context of 1MB multiple in non-large unit mode. Reliable
>> mode is enabled in the context based on whether reliable write is enabled.
>>
>> Signed-off-by: Saugata Das <saugata.das@xxxxxxxxxx>
>> ---
> The patch subject could be better off as "mmc: eMMC4.5 context ID support"
OK
>
>> drivers/mmc/card/block.c | 263 ++++++++++++++++++++++++++++++++++++++++++----
>> drivers/mmc/core/mmc.c | 6 +
>> include/linux/mmc/card.h | 13 +++
>> include/linux/mmc/core.h | 9 ++
>> include/linux/mmc/host.h | 1 +
>> include/linux/mmc/mmc.h | 3 +
>> 6 files changed, 275 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index 176b78e..161174a 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -127,6 +127,8 @@ enum mmc_blk_status {
>> module_param(perdev_minors, int, 0444);
>> MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device");
>>
>> +static int mmc_blk_issue_rw_rq(struct mmc_queue *, struct request *);
>> +
>> static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
>> {
>> struct mmc_blk_data *md;
>> @@ -1071,6 +1073,192 @@ static int mmc_blk_err_check(struct mmc_card *card,
>> return MMC_BLK_SUCCESS;
>> }
>>
>> +/*
>> + * Update the context information in the ext. CSD
>
> Mixed case
OK
>
>> + */
>> +static int mmc_context_modify(struct mmc_queue *mq,
>> + struct mmc_card *card,
>> + unsigned int context_id,
>> + unsigned char context_conf)
>> +{
>> + /*
>> + * Wait for any ongoing transfer
>> + */
>> + if (card->host->areq)
>> + mmc_blk_issue_rw_rq(mq, NULL);
>> +
>> + /*
>> + * CONTEXT_CONF array starts from context id 1
>> + */
>> + return mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> + EXT_CSD_CONTEXT_CONF + context_id - 1,
>> + context_conf,
>> + card->ext_csd.generic_cmd6_time);
>> +}
>> +
>> +/*
>> + * Update timestamp, size and close context if needed
>> + */
>> +static int mmc_check_close_context(struct mmc_queue *mq,
>> + struct mmc_card *card,
>> + unsigned int context_id,
>> + unsigned int status)
>> +{
>> + /*
>> + * Check only for valid contexts
>> + */
>> + if ((context_id > 0) &&
>> + (context_id <= card->ext_csd.max_context_id) &&
>> + (card->mmc_context[context_id].valid)) {
>> +
>> + /*
>> + * Incase of an error or we are multiple of erase block then
>> + * close the context
>> + */
>> + if ((status) ||
>> + ((card->mmc_context[context_id].size %
>> + card->ext_csd.lu_size) == 0)) {
>> + if (mmc_context_modify(mq, card, context_id,
>> + MMC_CONTEXT_CLOSE))
>> + return -1;
> Should propagate the error code instead of returning -1
>
OK
>> + card->mmc_context[context_id].valid = 0;
>> + }
>> + return 0;
>> + }
>> + return 0;
>> +}
>> +
>> +/*
>> + * Update timestamp, size and close context if needed
>> + */
>> +static int mmc_force_close_all_write_context(struct mmc_queue *mq,
>> + struct mmc_card *card)
>> +{
>> + int i, ret = 0;
>> + for (i = 1; i <= card->ext_csd.max_context_id; i++) {
>> + if (card->mmc_context[i].direction != MMC_CONTEXT_READ) {
>> + ret = mmc_check_close_context(mq, card, i,
>> + MMC_CONTEXT_FORCE_CLOSE);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> + return ret;
>> +}
>> +
>> +/*
>> + * Search for a context which is in the same direction and
>> + * continuous in block numbers. If no matching context is
>> + * found then take up an unused context. If all contexts are
>> + * used then close the context which is least recently used,
>> + * close it and the use it for the new transfer
>> + */
>> +static int mmc_get_context_id(struct mmc_queue *mq,
>> + struct mmc_card *card,
>> + unsigned int offset,
>> + unsigned int size,
>> + unsigned int direction,
>> + unsigned int rel_wr)
>> +{
>> + int i, free_index = -1, lru_index = -1, ret_index;
>> + unsigned int old_timestamp = -1;
>> + unsigned int reliability_mode = rel_wr ? (0x01<<5) : 0;
>> + struct mmc_context *context_ptr = &card->mmc_context[1];
>> +
>> + /*
>> + * For older than 4.5 eMMC, there is no context ID
>> + */
>> + if (card->ext_csd.max_context_id == 0)
>> + return 0;
>> +
>> + if (card->host->caps2 & MMC_CAP2_NO_CONTEXT)
>> + return 0;
>> +
>> + /*
>> + * If the request is LU size multiple then avoid
>> + * using any context
>> + */
>> + if ((size % card->ext_csd.lu_size) == 0)
>> + return 0;
>> +
>> + /*
>> + * Context 0 is unused
>> + */
>> + for (i = 1; i <= card->ext_csd.max_context_id; i++, context_ptr++) {
>> +
>> + unsigned int context_start_blk;
>> +
>> + if (!context_ptr->valid) {
>> + if (free_index == -1)
>> + free_index = i;
>> + continue;
>> + }
>> +
>> + context_start_blk = context_ptr->offset -
>> + context_ptr->size;
>> +
>> + if ((context_start_blk <= offset) &&
>> + (context_ptr->offset > offset)) {
>
> How would this condition ever match ? The starting offset of the
> previous request is usually less than the current request or it is
> more, but not both.
Perhaps the names are misleading. "context_ptr->offset" is the next
expected block number (i.e. 1 more than the last block number
transferred). "offset" is the start block number of the current
request. "context_start_blk" is the first block number of the context.
The idea was to make sure that we do not access back some previous
block within the context. I will change the name of
"context_ptr->offset" to "context_ptr->next_blk" and "offset" to
"current_req_start_blk". Is it OK for you ?
Note that, the spec does not prevent us from random or overlapping
access within a context in non-LU mode. But the spec is strict for LU
mode and I followed the principles of LU mode transfers in non-LU mode
because I assumed eMMC performance would be more optimized with such
restrictions.
>
>> + int ret = mmc_check_close_context(mq, card, i,
>> + MMC_CONTEXT_FORCE_CLOSE);
>> + if (ret < 0)
>> + return ret;
>> + if (free_index == -1)
>> + free_index = i;
>> + break;
>> + }
>> +
>> + if ((lru_index == -1) ||
>> + (context_ptr->timestamp < old_timestamp)) {
>> + old_timestamp = context_ptr->timestamp;
>> + lru_index = i;
>> + }
>> +
>> + if ((context_ptr->direction != direction) ||
>> + (context_ptr->offset != offset) ||
>> + (context_ptr->reliability_mode !=
>> + reliability_mode))
>> + continue;
>
> I think the reliability mode match shouldn't matter. If the writes to
> the same section of the device, the best of the reliability modes can
> be applied.
Once the reliability of the context is chosen then the individual
writes reliability bit (in CMD23) will be ignored. So, if some writes
need reliability, it needs to check for the reliable context.
> This section should be moved above the context_start_blk and offset
> checking code.
On the same pass of the "for" loop we are trying to set the
"lru_index". The current place is OK, in my view.
> Why close an ongoing context if the directions don't match eventually ?
We open a context with a specific direction (read or write). If
direction do not match, then we can not use that context.
>
>> +
>> + context_ptr->timestamp = jiffies;
>> + context_ptr->offset += size;
>> + context_ptr->size += size;
>> + return i;
>> + }
>> +
>> + if (free_index != -1) {
>> + /*
>> + * Open a free context
>> + */
>> + if (mmc_context_modify(mq, card, free_index,
>> + (direction & 0x03) | reliability_mode))
>> + return -1;
>> + ret_index = free_index;
>> + } else if (lru_index != -1) {
>> + /*
>> + * Close and reopen the LRU context
>> + */
>> + if (mmc_context_modify(mq, card, lru_index, MMC_CONTEXT_CLOSE))
>> + return -1;
>> +
>> + if (mmc_context_modify(mq, card, lru_index,
>> + (direction & 0x03) | reliability_mode))
>> + return -1;
>> + ret_index = lru_index;
>> + } else
>> + return -1;
>> +
>> + context_ptr = &card->mmc_context[ret_index];
>> + context_ptr->offset = offset+size;
>> + context_ptr->size = size;
>> + context_ptr->direction = direction;
>> + context_ptr->timestamp = jiffies;
>> + context_ptr->reliability_mode = reliability_mode;
>> + context_ptr->valid = 1;
>> +
>> + return ret_index;
>> +}
>> +
>> static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>> struct mmc_card *card,
>> int disable_multi,
>> @@ -1080,7 +1268,6 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>> struct mmc_blk_request *brq = &mqrq->brq;
>> struct request *req = mqrq->req;
>> struct mmc_blk_data *md = mq->data;
>> - bool do_data_tag;
>>
>> /*
>> * Reliable writes are used to implement Forced Unit Access and
>> @@ -1157,16 +1344,6 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>> mmc_apply_rel_rw(brq, card, req);
>>
>> /*
>> - * Data tag is used only during writing meta data to speed
>> - * up write and any subsequent read of this meta data
>> - */
>> - do_data_tag = (card->ext_csd.data_tag_unit_size) &&
>> - (req->cmd_flags & REQ_META) &&
>> - (rq_data_dir(req) == WRITE) &&
>> - ((brq->data.blocks * brq->data.blksz) >=
>> - card->ext_csd.data_tag_unit_size);
>> -
>> - /*
>> * Pre-defined multi-block transfers are preferable to
>> * open ended-ones (and necessary for reliable writes).
>> * However, it is not sufficient to just send CMD23,
>> @@ -1184,15 +1361,54 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>> * We'll avoid using CMD23-bounded multiblock writes for
>> * these, while retaining features like reliable writes.
>> */
>> - if ((md->flags & MMC_BLK_CMD23) && mmc_op_multi(brq->cmd.opcode) &&
>> - (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23) ||
>> - do_data_tag)) {
>> - brq->sbc.opcode = MMC_SET_BLOCK_COUNT;
>> - brq->sbc.arg = brq->data.blocks |
>> - (do_rel_wr ? (1 << 31) : 0) |
>> - (do_data_tag ? (1 << 29) : 0);
>> - brq->sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
>> - brq->mrq.sbc = &brq->sbc;
>> + if ((md->flags & MMC_BLK_CMD23) && mmc_op_multi(brq->cmd.opcode)) {
>> + /*
>> + * Context ID is used for non-large unit and non-reliable
>> + * write transfers provided the start block number
>> + * sequentially follows any of the open contexts
>> + */
>> + int context_id;
>> +
>> + /*
>> + * Data tag is used only during writing meta data to speed
>> + * up write and any subsequent read of this meta data
>> + */
>> + bool do_data_tag = (card->ext_csd.data_tag_unit_size) &&
>> + (req->cmd_flags & REQ_META) &&
>> + (rq_data_dir(req) == WRITE) &&
>> + ((brq->data.blocks * brq->data.blksz) >=
>> + card->ext_csd.data_tag_unit_size);
>> +
>> + /*
>> + * During fsync, ensure that data is committed to storage
>> + */
>> + if (req->cmd_flags & (REQ_FLUSH | REQ_SYNC))
>> + mmc_force_close_all_write_context(mq, card);
>> +
>> + /*
>> + * Context ID is used for non-large unit and non-reliable
>> + * write transfers provided the start block number
>> + * sequentially follows any of the open contexts
>> + */
>> + context_id = mmc_get_context_id(mq,
>> + card,
>> + blk_rq_pos(req),
>> + brq->data.blocks,
>> + (rq_data_dir(req) == WRITE) ? MMC_CONTEXT_WRITE :
>> + MMC_CONTEXT_READ,
>> + do_rel_wr);
>> +
>> + if (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23) ||
>> + do_data_tag || (context_id > 0)) {
>> + brq->sbc.opcode = MMC_SET_BLOCK_COUNT;
>> + brq->sbc.arg = brq->data.blocks |
>> + (do_rel_wr ? (1 << 31) : 0) |
>> + (do_data_tag ? (1 << 29) : 0) |
>> + (((context_id > 0) && (!do_rel_wr)) ?
>> + ((context_id & 0x0f) << 25) : 0);
>> + brq->sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
>> + brq->mrq.sbc = &brq->sbc;
>> + }
>> }
>>
>> mmc_set_data_timeout(&brq->data, card);
>> @@ -1284,6 +1500,13 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
>> type = rq_data_dir(req) == READ ? MMC_BLK_READ : MMC_BLK_WRITE;
>> mmc_queue_bounce_post(mq_rq);
>>
>> + if (mmc_check_close_context(mq,
>> + card,
>> + ((brq->sbc.arg) >> 25) & 0x0f,
>> + status) < 0) {
>> + status = MMC_BLK_CMD_ERR;
>> + }
>> +
>> switch (status) {
>> case MMC_BLK_SUCCESS:
>> case MMC_BLK_PARTIAL:
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index dc03291..469d100 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -533,6 +533,12 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
>> } else {
>> card->ext_csd.data_tag_unit_size = 0;
>> }
>> +
>> + /* LU size in 512 byte sectors */
>> + card->ext_csd.lu_size =
>> + (ext_csd[EXT_CSD_LARGE_UNIT_SIZE_M1] + 1) * 0x800;
>> + card->ext_csd.max_context_id =
>> + ext_csd[EXT_CSD_CONTEXT_CAPABILITIES] & 0x0f;
>> }
>>
>> out:
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index f9a0663..2e5b85a 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -73,6 +73,8 @@ struct mmc_ext_csd {
>> unsigned int hpi_cmd; /* cmd used as HPI */
>> unsigned int data_sector_size; /* 512 bytes or 4KB */
>> unsigned int data_tag_unit_size; /* DATA TAG UNIT size */
>> + unsigned int lu_size;
>> + unsigned int max_context_id;
>> unsigned int boot_ro_lock; /* ro lock support */
>> bool boot_ro_lockable;
>> u8 raw_partition_support; /* 160 */
>> @@ -184,6 +186,16 @@ struct sdio_func_tuple;
>> #define MAX_MMC_PART_NAME_LEN 20
>>
>> /*
>> + * Contexts can be upto 15
>> + */
>> +#define MMC_NUM_CONTEXT 15
>> +#define MMC_CONTEXT_CLOSE 0
>> +#define MMC_CONTEXT_WRITE 1
>> +#define MMC_CONTEXT_READ 2
>> +
>> +#define MMC_CONTEXT_FORCE_CLOSE 1
>> +
>> +/*
>> * MMC Physical partitions
>> */
>> struct mmc_part {
>> @@ -268,6 +280,7 @@ struct mmc_card {
>> struct dentry *debugfs_root;
>> struct mmc_part part[MMC_NUM_PHY_PARTITION]; /* physical partitions */
>> unsigned int nr_parts;
>> + struct mmc_context mmc_context[MMC_NUM_CONTEXT];
>> };
>>
>> /*
>> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
>> index 87a976c..f20ebc5 100644
>> --- a/include/linux/mmc/core.h
>> +++ b/include/linux/mmc/core.h
>> @@ -130,6 +130,15 @@ struct mmc_request {
>> void (*done)(struct mmc_request *);/* completion function */
>> };
>>
>> +struct mmc_context {
>> + unsigned int offset;
>> + unsigned int size;
>> + unsigned int direction;
>> + unsigned int timestamp;
>> + unsigned int reliability_mode;
>> + unsigned int valid;
>> +};
>> +
>> struct mmc_host;
>> struct mmc_card;
>> struct mmc_async_req;
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index dd13e05..661e262 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -255,6 +255,7 @@ struct mmc_host {
>> #define MMC_CAP2_NO_SLEEP_CMD (1 << 4) /* Don't allow sleep command */
>> #define MMC_CAP2_HS200_1_8V_SDR (1 << 5) /* can support */
>> #define MMC_CAP2_HS200_1_2V_SDR (1 << 6) /* can support */
>> +#define MMC_CAP2_NO_CONTEXT (1 << 7) /* context ID not supported */
>> #define MMC_CAP2_HS200 (MMC_CAP2_HS200_1_8V_SDR | \
>> MMC_CAP2_HS200_1_2V_SDR)
>>
>> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
>> index b822a2c..809c3a5 100644
>> --- a/include/linux/mmc/mmc.h
>> +++ b/include/linux/mmc/mmc.h
>> @@ -274,6 +274,7 @@ struct _mmc_csd {
>> #define EXT_CSD_FLUSH_CACHE 32 /* W */
>> #define EXT_CSD_CACHE_CTRL 33 /* R/W */
>> #define EXT_CSD_POWER_OFF_NOTIFICATION 34 /* R/W */
>> +#define EXT_CSD_CONTEXT_CONF 37 /* R/W : array of 15 config */
>> #define EXT_CSD_DATA_SECTOR_SIZE 61 /* R */
>> #define EXT_CSD_GP_SIZE_MULT 143 /* R/W */
>> #define EXT_CSD_PARTITION_ATTRIBUTE 156 /* R/W */
>> @@ -316,6 +317,8 @@ struct _mmc_csd {
>> #define EXT_CSD_POWER_OFF_LONG_TIME 247 /* RO */
>> #define EXT_CSD_GENERIC_CMD6_TIME 248 /* RO */
>> #define EXT_CSD_CACHE_SIZE 249 /* RO, 4 bytes */
>> +#define EXT_CSD_LARGE_UNIT_SIZE_M1 495 /* RO */
>> +#define EXT_CSD_CONTEXT_CAPABILITIES 496 /* RO */
>> #define EXT_CSD_TAG_UNIT_SIZE 498 /* RO */
>> #define EXT_CSD_DATA_TAG_SUPPORT 499 /* RO */
>> #define EXT_CSD_HPI_FEATURES 503 /* RO */
>> --
>> 1.7.4.3
>>
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