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SubjectRE: [PATCH v6 1/3] mmc: core: Add packed command feature of eMMC4.5
Date
Subhash Jadavani <subhashj@codeaurora.org> wrote:
> Hi Seungwon,
>
> Sorry for commenting on this late. I have one comment below. Please
> check if it makes sense or not.
>
> On 5/17/2012 3:10 PM, Seungwon Jeon wrote:
> > This patch adds packed command feature of eMMC4.5.
> > The maximum number for packing read(or write) is offered
> > and exception event relevant to packed command which is
> > used for error handling is enabled. If host wants to use
> > this feature, MMC_CAP2_PACKED_CMD should be set.
> >
> > Signed-off-by: Seungwon Jeon<tgih.jun@samsung.com>
> > ---
> > drivers/mmc/core/mmc.c | 24 ++++++++++++++++++++++++
> > include/linux/mmc/card.h | 3 +++
> > include/linux/mmc/host.h | 4 ++++
> > include/linux/mmc/mmc.h | 15 +++++++++++++++
> > 4 files changed, 46 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index 2f0e11c..8310ce8 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -516,6 +516,11 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
> > } else {
> > card->ext_csd.data_tag_unit_size = 0;
> > }
> > +
> > + card->ext_csd.max_packed_writes =
> > + ext_csd[EXT_CSD_MAX_PACKED_WRITES];
> > + card->ext_csd.max_packed_reads =
> > + ext_csd[EXT_CSD_MAX_PACKED_READS];
> > }
> >
> > out:
> > @@ -1244,6 +1249,25 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> > }
> > }
> >
> > + if ((host->caps2& MMC_CAP2_PACKED_CMD)&&
> > + (card->ext_csd.max_packed_writes> 0)&&
> > + (card->ext_csd.max_packed_reads> 0)) {
> why both max_packed_reads and max_packed_writes need to be non-zero to
> enable the write packing event? What if write packing is not supported
> by card and only read packing is supported? Shouldn't we still make the
> read packing work?
I have not experienced that case. But it seems like possible actually.
Spec doesn't mention two should be satisfied for packed command.
I'll apply your comment.

Best regards,
Seungwon Jeon
>
> I would suggest to change it like this:
> if ( (host->caps2 & MMC_CAP2_PACKED_WR &&
> card->ext_csd.max_packed_writes > 0) ||
> (host->caps2 & MMC_CAP2_PACKED_RD &&
> card->ext_csd.max_packed_reads > 0)
> > + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > + EXT_CSD_EXP_EVENTS_CTRL,
> > + EXT_CSD_PACKED_EVENT_EN,
> > + card->ext_csd.generic_cmd6_time);
> > + if (err&& err != -EBADMSG)
> > + goto free_card;
> > + if (err) {
> > + pr_warning("%s: Enabling packed event failed\n",
> > + mmc_hostname(card->host));
> > + card->ext_csd.packed_event_en = 0;
> > + err = 0;
> > + } else {
> > + card->ext_csd.packed_event_en = 1;
> > + }
> > + }
> > +
> > if (!oldcard)
> > host->card = card;
> >
> > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> > index d76513b..4aeb4e9 100644
> > --- a/include/linux/mmc/card.h
> > +++ b/include/linux/mmc/card.h
> > @@ -53,6 +53,9 @@ struct mmc_ext_csd {
> > u8 part_config;
> > u8 cache_ctrl;
> > u8 rst_n_function;
> > + u8 max_packed_writes;
> > + u8 max_packed_reads;
> > + u8 packed_event_en;
> > unsigned int part_time; /* Units: ms */
> > unsigned int sa_timeout; /* Units: 100ns */
> > unsigned int generic_cmd6_time; /* Units: 10ms */
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index 0707d22..9d0d946 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -238,6 +238,10 @@ struct mmc_host {
> > #define MMC_CAP2_BROKEN_VOLTAGE (1<< 7) /* Use the broken voltage */
> > #define MMC_CAP2_DETECT_ON_ERR (1<< 8) /* On I/O err check card removal */
> > #define MMC_CAP2_HC_ERASE_SZ (1<< 9) /* High-capacity erase size */
> > +#define MMC_CAP2_PACKED_RD (1<< 10) /* Allow packed read */
> > +#define MMC_CAP2_PACKED_WR (1<< 11) /* Allow packed write */
> > +#define MMC_CAP2_PACKED_CMD (MMC_CAP2_PACKED_RD | \
> > + MMC_CAP2_PACKED_WR) /* Allow packed commands */
> >
> > mmc_pm_flag_t pm_caps; /* supported pm features */
> > unsigned int power_notify_type;
> > diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
> > index d425cab..254901a 100644
> > --- a/include/linux/mmc/mmc.h
> > +++ b/include/linux/mmc/mmc.h
> > @@ -139,6 +139,7 @@ static inline bool mmc_op_multi(u32 opcode)
> > #define R1_CURRENT_STATE(x) ((x& 0x00001E00)>> 9) /* sx, b (4 bits) */
> > #define R1_READY_FOR_DATA (1<< 8) /* sx, a */
> > #define R1_SWITCH_ERROR (1<< 7) /* sx, c */
> > +#define R1_EXP_EVENT (1<< 6) /* sr, a */
> > #define R1_APP_CMD (1<< 5) /* sr, c */
> >
> > #define R1_STATE_IDLE 0
> > @@ -274,6 +275,10 @@ 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_PACKED_FAILURE_INDEX 35 /* RO */
> > +#define EXT_CSD_PACKED_CMD_STATUS 36 /* RO */
> > +#define EXT_CSD_EXP_EVENTS_STATUS 54 /* RO, 2 bytes */
> > +#define EXT_CSD_EXP_EVENTS_CTRL 56 /* R/W, 2 bytes */
> > #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 */
> > @@ -318,6 +323,8 @@ struct _mmc_csd {
> > #define EXT_CSD_CACHE_SIZE 249 /* RO, 4 bytes */
> > #define EXT_CSD_TAG_UNIT_SIZE 498 /* RO */
> > #define EXT_CSD_DATA_TAG_SUPPORT 499 /* RO */
> > +#define EXT_CSD_MAX_PACKED_WRITES 500 /* RO */
> > +#define EXT_CSD_MAX_PACKED_READS 501 /* RO */
> > #define EXT_CSD_HPI_FEATURES 503 /* RO */
> >
> > /*
> > @@ -377,6 +384,14 @@ struct _mmc_csd {
> > #define EXT_CSD_PWR_CL_4BIT_MASK 0x0F /* 8 bit PWR CLS */
> > #define EXT_CSD_PWR_CL_8BIT_SHIFT 4
> > #define EXT_CSD_PWR_CL_4BIT_SHIFT 0
> > +
> > +#define EXT_CSD_PACKED_EVENT_EN (1<< 3)
> > +
> > +#define EXT_CSD_PACKED_FAILURE (1<< 3)
> > +
> > +#define EXT_CSD_PACKED_GENERIC_ERROR (1<< 0)
> > +#define EXT_CSD_PACKED_INDEXED_ERROR (1<< 1)
> > +
> > /*
> > * MMC_SWITCH access modes
> > */
>
> --
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