Hi Andrei.
I have some question..
In mmc_blk_issue_rw_rq() of block.c, there is the below code.
static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
{
struct mmc_blk_data *md = mq->data;
struct mmc_card *card = md->queue.card;
struct mmc_blk_request brq;
int ret = 1, disable_multi = 0;
/*
* Reliable writes are used to implement Forced Unit Access and
* REQ_META accesses, and are supported only on MMCs.
*/
bool do_rel_wr = ((req->cmd_flags & REQ_FUA) ||
(req->cmd_flags & REQ_META)) &&
(rq_data_dir(req) == WRITE) &&
REL_WRITES_SUPPORTED(card);
do {
struct mmc_command cmd = {0};
u32 readcmd, writecmd, status = 0;
memset(&brq, 0, sizeof(struct mmc_blk_request));
brq.mrq.cmd = &brq.cmd;
brq.mrq.data = &brq.data;
brq.cmd.arg = blk_rq_pos(req);
if (!mmc_card_blockaddr(card))
brq.cmd.arg <<= 9;
brq.cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
brq.data.blksz = 512;
brq.stop.opcode = MMC_STOP_TRANSMISSION;
brq.stop.arg = 0;
brq.stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
brq.data.blocks = blk_rq_sectors(req);
There is "brq.stop.opcode = MMC_STOP_TRANSMISSION".
If we use CMD23, this line didn't need? Actually i don't know, so i ask to you.
Regards,
Jaehoon Chung
Andrei Warkentin wrote:
> CMD23-prefixed instead of open-ended multiblock transfers
> have a performance advantage on some MMC cards.
>
> Cc: arindam.n...@amd.com
> Cc: c...@laptop.org
> Cc: a...@arndb.de
> Cc: malc...@google.com
> Signed-off-by: Andrei Warkentin <andr...@motorola.com>
> ---
> drivers/mmc/card/block.c | 108 +++++++++++++++++++++++++++++++++------------
> include/linux/mmc/card.h | 1 +
> include/linux/mmc/core.h | 1 +
> include/linux/mmc/host.h | 6 +++
> include/linux/mmc/mmc.h | 6 +++
> 5 files changed, 93 insertions(+), 29 deletions(-)
> mode change 100644 => 100755 drivers/mmc/card/block.c
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> old mode 100644
> new mode 100755
> index 126c7f4..a380acc
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -59,10 +59,6 @@ MODULE_ALIAS("mmc:block");
> #define INAND_CMD38_ARG_SECTRIM1 0x81
> #define INAND_CMD38_ARG_SECTRIM2 0x88
>
> -#define REL_WRITES_SUPPORTED(card) (mmc_card_mmc((card)) && \
> - (((card)->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN) || \
> - ((card)->ext_csd.rel_sectors)))
> -
> static DEFINE_MUTEX(block_mutex);
>
> /*
> @@ -90,6 +86,10 @@ struct mmc_blk_data {
> struct mmc_queue queue;
> struct list_head part;
>
> + unsigned int flags;
> +#define MMC_BLK_CMD23 (1 << 0) /* Can do SET_BLOCK_COUNT for
> multiblock */
> +#define MMC_BLK_REL_WR (1 << 1) /* MMC Reliable write support */
> +
> unsigned int usage;
> unsigned int read_only;
> unsigned int part_type;
> @@ -429,6 +429,7 @@ static const struct block_device_operations mmc_bdops = {
>
> struct mmc_blk_request {
> struct mmc_request mrq;
> + struct mmc_command sbc;
> struct mmc_command cmd;
> struct mmc_command stop;
> struct mmc_data data;
> @@ -652,13 +653,10 @@ static int mmc_blk_issue_flush(struct mmc_queue *mq,
> struct request *req)
> * reliable write can handle, thus finish the request in
> * partial completions.
> */
> -static inline int mmc_apply_rel_rw(struct mmc_blk_request *brq,
> - struct mmc_card *card,
> - struct request *req)
> +static inline void mmc_apply_rel_rw(struct mmc_blk_request *brq,
> + struct mmc_card *card,
> + struct request *req)
> {
> - int err;
> - struct mmc_command set_count = {0};
> -
> if (!(card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN)) {
> /* Legacy mode imposes restrictions on transfers. */
> if (!IS_ALIGNED(brq->cmd.arg, card->ext_csd.rel_sectors))
> @@ -669,15 +667,6 @@ static inline int mmc_apply_rel_rw(struct
> mmc_blk_request *brq,
> else if (brq->data.blocks < card->ext_csd.rel_sectors)
> brq->data.blocks = 1;
> }
> -
> - set_count.opcode = MMC_SET_BLOCK_COUNT;
> - set_count.arg = brq->data.blocks | (1 << 31);
> - set_count.flags = MMC_RSP_R1 | MMC_CMD_AC;
> - err = mmc_wait_for_cmd(card->host, &set_count, 0);
> - if (err)
> - printk(KERN_ERR "%s: error %d SET_BLOCK_COUNT\n",
> - req->rq_disk->disk_name, err);
> - return err;
> }
>
> static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
> @@ -694,7 +683,7 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *req)
> bool do_rel_wr = ((req->cmd_flags & REQ_FUA) ||
> (req->cmd_flags & REQ_META)) &&
> (rq_data_dir(req) == WRITE) &&
> - REL_WRITES_SUPPORTED(card);
> + (md->flags & MMC_BLK_REL_WR);
>
> do {
> struct mmc_command cmd = {0};
> @@ -732,11 +721,9 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *req)
>
> if (brq.data.blocks > 1 || do_rel_wr) {
> /* SPI multiblock writes terminate using a special
> - * token, not a STOP_TRANSMISSION request. Reliable
> - * writes use SET_BLOCK_COUNT and do not use a
> - * STOP_TRANSMISSION request either.
> + * token, not a STOP_TRANSMISSION request.
> */
> - if ((!mmc_host_is_spi(card->host) && !do_rel_wr) ||
> + if (!mmc_host_is_spi(card->host) ||
> rq_data_dir(req) == READ)
> brq.mrq.stop = &brq.stop;
> readcmd = MMC_READ_MULTIPLE_BLOCK;
> @@ -754,8 +741,37 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *req)
> brq.data.flags |= MMC_DATA_WRITE;
> }
>
> - if (do_rel_wr && mmc_apply_rel_rw(&brq, card, req))
> - goto cmd_err;
> + if (do_rel_wr)
> + mmc_apply_rel_rw(&brq, card, req);
> +
> + /*
> + * 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,
> + * and avoid the final CMD12, as on an error condition
> + * CMD12 (stop) needs to be sent anyway. This, coupled
> + * with Auto-CMD23 enhancements provided by some
> + * hosts, means that the complexity of dealing
> + * with this is best left to the host. If CMD23 is
> + * supported by card and host, we'll fill sbc in and let
> + * the host deal with handling it correctly. This means
> + * that for hosts that don't expose MMC_CAP_CMD23, no
> + * change of behavior will be observed.
> + *
> + * N.B: Some MMC cards experience perf degradation.
> + * 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))) {
> + brq.sbc.opcode = MMC_SET_BLOCK_COUNT;
> + brq.sbc.arg = brq.data.blocks |
> + (do_rel_wr ? (1 << 31) : 0);
> + brq.sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
> + brq.mrq.sbc = &brq.sbc;
> + }
>
> mmc_set_data_timeout(&brq.data, card);
>
> @@ -792,7 +808,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *req)
> * until later as we need to wait for the card to leave
> * programming mode even when things go wrong.
> */
> - if (brq.cmd.error || brq.data.error || brq.stop.error) {
> + if (brq.sbc.error || brq.cmd.error ||
> + brq.data.error || brq.stop.error) {
> if (brq.data.blocks > 1 && rq_data_dir(req) == READ) {
> /* Redo read one sector at a time */
> printk(KERN_WARNING "%s: retrying using single "
> @@ -803,6 +820,13 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
> struct request *req)
> status = get_card_status(card, req);
> }
>
> + if (brq.sbc.error) {
> + printk(KERN_ERR "%s: error %d sending SET_BLOCK_COUNT "
> + "command, response %#x, card status %#x\n",
> + req->rq_disk->disk_name, brq.sbc.error,
> + brq.sbc.resp[0], status);
> + }
> +
> if (brq.cmd.error) {
> printk(KERN_ERR "%s: error %d sending read/write "
> "command, response %#x, card status %#x\n",
> @@ -1014,8 +1038,6 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct
> mmc_card *card,
> md->disk->queue = md->queue.queue;
> md->disk->driverfs_dev = parent;
> set_disk_ro(md->disk, md->read_only || default_ro);
> - if (REL_WRITES_SUPPORTED(card))
> - blk_queue_flush(md->queue.queue, REQ_FLUSH | REQ_FUA);
>
> /*
> * As discussed on lkml, GENHD_FL_REMOVABLE should:
> @@ -1034,6 +1056,19 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct
> mmc_card *card,
>
> blk_queue_logical_block_size(md->queue.queue, 512);
> set_capacity(md->disk, size);
> +
> + if (mmc_host_cmd23(card->host) &&
> + mmc_card_mmc(card))
> + md->flags |= MMC_BLK_CMD23;
> +
> + if (mmc_card_mmc(card) &&
> + md->flags & MMC_BLK_CMD23 &&
> + ((card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN) ||
> + card->ext_csd.rel_sectors)) {
> + md->flags |= MMC_BLK_REL_WR;
> + blk_queue_flush(md->queue.queue, REQ_FLUSH | REQ_FUA);
> + }
> +
> return md;
>
> err_putdisk:
> @@ -1189,6 +1224,21 @@ static const struct mmc_fixup blk_fixups[] =
> MMC_FIXUP("SEM08G", 0x2, 0x100, add_quirk, MMC_QUIRK_INAND_CMD38),
> MMC_FIXUP("SEM16G", 0x2, 0x100, add_quirk, MMC_QUIRK_INAND_CMD38),
> MMC_FIXUP("SEM32G", 0x2, 0x100, add_quirk, MMC_QUIRK_INAND_CMD38),
> +
> + /*
> + * Some MMC cards experience performance degradation with CMD23
> + * instead of CMD12-bounded multiblock transfers. For now we'll
> + * black list what's bad...
> + * - Certain Toshiba cards.
> + *
> + * N.B. This doesn't affect SD cards.
> + */
> + MMC_FIXUP("MMC08G", 0x11, CID_OEMID_ANY, add_quirk_mmc,
> + MMC_QUIRK_BLK_NO_CMD23),
> + MMC_FIXUP("MMC16G", 0x11, CID_OEMID_ANY, add_quirk_mmc,
> + MMC_QUIRK_BLK_NO_CMD23),
> + MMC_FIXUP("MMC32G", 0x11, CID_OEMID_ANY, add_quirk_mmc,
> + MMC_QUIRK_BLK_NO_CMD23),
> END_FIXUP
> };
>
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 7190aa2..4a0e27b 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -171,6 +171,7 @@ struct mmc_card {
> #define MMC_QUIRK_NONSTD_FUNC_IF (1<<4) /* SDIO card has nonstd
> function interfaces */
> #define MMC_QUIRK_DISABLE_CD (1<<5) /* disconnect CD/DAT[3]
> resistor */
> #define MMC_QUIRK_INAND_CMD38 (1<<6) /* iNAND devices have
> broken CMD38 */
> +#define MMC_QUIRK_BLK_NO_CMD23 (1<<7) /* Avoid CMD23 for
> regular multiblock */
>
> unsigned int erase_size; /* erase size in sectors */
> unsigned int erase_shift; /* if erase unit is power 2 */
> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> index cbe8d55..b6718e5 100644
> --- a/include/linux/mmc/core.h
> +++ b/include/linux/mmc/core.h
> @@ -120,6 +120,7 @@ struct mmc_data {
> };
>
> struct mmc_request {
> + struct mmc_command *sbc; /* SET_BLOCK_COUNT for
> multiblock */
> struct mmc_command *cmd;
> struct mmc_data *data;
> struct mmc_command *stop;
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index de32e6a..e946bd1 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -210,6 +210,7 @@ struct mmc_host {
> #define MMC_CAP_MAX_CURRENT_400 (1 << 27) /* Host max current
> limit is 400mA */
> #define MMC_CAP_MAX_CURRENT_600 (1 << 28) /* Host max current
> limit is 600mA */
> #define MMC_CAP_MAX_CURRENT_800 (1 << 29) /* Host max current
> limit is 800mA */
> +#define MMC_CAP_CMD23 (1 << 30) /* CMD23 supported. */
>
> mmc_pm_flag_t pm_caps; /* supported pm features */
>
> @@ -366,5 +367,10 @@ static inline int mmc_card_wake_sdio_irq(struct mmc_host
> *host)
> {
> return host->pm_flags & MMC_PM_WAKE_SDIO_IRQ;
> }
> +
> +static inline int mmc_host_cmd23(struct mmc_host *host)
> +{
> + return host->caps & MMC_CAP_CMD23;
> +}
> #endif
>
> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
> index 9fa5a73..848aab2 100644
> --- a/include/linux/mmc/mmc.h
> +++ b/include/linux/mmc/mmc.h
> @@ -83,6 +83,12 @@
> #define MMC_APP_CMD 55 /* ac [31:16] RCA R1 */
> #define MMC_GEN_CMD 56 /* adtc [0] RD/WR R1 */
>
> +static inline bool mmc_op_multi(u32 opcode)
> +{
> + return opcode == MMC_WRITE_MULTIPLE_BLOCK ||
> + opcode == MMC_READ_MULTIPLE_BLOCK;
> +}
> +
> /*
> * MMC_SWITCH argument format:
> *
--
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