On 2016/5/9 19:56, Adrian Hunter wrote:
> On 29/04/16 05:47, Shawn Lin wrote:
>> Controllers use data strobe line to latch data from devices
>> under hs400 mode, but not for cmd line. So since emmc 5.1, JEDEC
>> introduces enhanced strobe mode for latching cmd response from
>> emmc devices to host controllers. This new feature is optional,
>> so it depends both on device's cap and host's cap to decide
>> whether to use it or not.
>>
>> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
>
> Thanks for doing this. There are a couple of comments below, but generally
> I tend to think you should split out selecting HS400ES as a separate function.
>
>> ---
>>
>> Changes in v2: None
>>
>> drivers/mmc/core/bus.c | 3 +-
>> drivers/mmc/core/mmc.c | 77 ++++++++++++++++++++++++++++++++++++++++++++----
>> include/linux/mmc/card.h | 1 +
>> include/linux/mmc/host.h | 12 ++++++++
>> include/linux/mmc/mmc.h | 3 ++
>> 5 files changed, 89 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
>> index 4bc48f1..7e94b9d 100644
>> --- a/drivers/mmc/core/bus.c
>> +++ b/drivers/mmc/core/bus.c
>> @@ -332,12 +332,13 @@ int mmc_add_card(struct mmc_card *card)
>> mmc_card_ddr52(card) ? "DDR " : "",
>> type);
>> } else {
>> - pr_info("%s: new %s%s%s%s%s card at address %04x\n",
>> + pr_info("%s: new %s%s%s%s%s%s card at address %04x\n",
>> mmc_hostname(card->host),
>> mmc_card_uhs(card) ? "ultra high speed " :
>> (mmc_card_hs(card) ? "high speed " : ""),
>> mmc_card_hs400(card) ? "HS400 " :
>> (mmc_card_hs200(card) ? "HS200 " : ""),
>> + mmc_card_hs400es(card) ? "Enhanced strobe" : "",
>> mmc_card_ddr52(card) ? "DDR " : "",
>> uhs_bus_speed_mode, type, card->rca);
>> }
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 28b477d..f45ed10 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -235,6 +235,12 @@ static void mmc_select_card_type(struct mmc_card *card)
>> avail_type |= EXT_CSD_CARD_TYPE_HS400_1_2V;
>> }
>>
>> + if ((caps2 & MMC_CAP2_HS400_ENHANCED_STROBE) &&
>> + card->ext_csd.strobe_support &&
>> + ((card_type & EXT_CSD_CARD_TYPE_HS400_1_2V) ||
>> + (card_type & EXT_CSD_CARD_TYPE_HS400_1_8V)))
>
> Could use just "card_type & EXT_CSD_CARD_TYPE_HS400" here
okay, EXT_CSD_CARD_TYPE_HS400 contains 1_2V & 1_8V, so I will
use it.
>
>> + avail_type |= EXT_CSD_CARD_TYPE_HS400ES;
>> +
>> card->ext_csd.hs_max_dtr = hs_max_dtr;
>> card->ext_csd.hs200_max_dtr = hs200_max_dtr;
>> card->mmc_avail_type = avail_type;
>> @@ -383,6 +389,7 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
>> mmc_card_set_blockaddr(card);
>> }
>>
>> + card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT];
>> card->ext_csd.raw_card_type = ext_csd[EXT_CSD_CARD_TYPE];
>> mmc_select_card_type(card);
>>
>> @@ -1062,9 +1069,10 @@ static int mmc_select_hs400(struct mmc_card *card)
>> u8 val;
>>
>> /*
>> - * HS400 mode requires 8-bit bus width
>> + * HS400(ES) mode requires 8-bit bus width
>> */
>> - if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&
>> + if (!(((card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400) ||
>> + (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)) &&
>> host->ios.bus_width == MMC_BUS_WIDTH_8))
>> return 0;
>>
>> @@ -1097,9 +1105,26 @@ static int mmc_select_hs400(struct mmc_card *card)
>> }
>>
>> /* Switch card to DDR */
>> + val = EXT_CSD_DDR_BUS_WIDTH_8;
>> + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
>> + val |= EXT_CSD_BUS_WIDTH_STROBE;
>> + /*
>> + * Make sure we are in non-enhanced strobe mode before we
>> + * actually enable it in ext_csd.
>> + */
>> + if (host->ops->prepare_enhanced_strobe)
>> + err = host->ops->prepare_enhanced_strobe(host, false);
>> +
>> + if (err) {
>> + pr_err("%s: unprepare_enhanced strobe failed, err:%d\n",
>> + mmc_hostname(host), err);
>> + return err;
>> + }
>> + }
>> +
>> err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> EXT_CSD_BUS_WIDTH,
>> - EXT_CSD_DDR_BUS_WIDTH_8,
>> + val,
>> card->ext_csd.generic_cmd6_time);
>> if (err) {
>> pr_err("%s: switch to bus width for hs400 failed, err:%d\n",
>> @@ -1124,6 +1149,35 @@ static int mmc_select_hs400(struct mmc_card *card)
>> mmc_set_timing(host, MMC_TIMING_MMC_HS400);
>> mmc_set_bus_speed(card);
>>
>> + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
>> + /* Controller enable enhanced strobe function */
>> + if (host->ops->prepare_enhanced_strobe)
>> + err = host->ops->prepare_enhanced_strobe(host, true);
>> +
>> + if (err) {
>> + pr_err("%s: prepare enhanced strobe failed, err:%d\n",
>> + mmc_hostname(host), err);
>> + return err;
>> + }
>> +
>> + /*
>> + * After switching to hs400 enhanced strobe mode, we expect to
>> + * verify whether it works or not. If controller can't handle
>> + * bus width test, compare ext_csd previously read in 1 bit mode
>> + * against ext_csd at new bus width
>> + */
>
> I don't think we need this. Just checking (host->caps & MMC_CAP_8_BIT_DATA)
> ought to be enough. But if you want to play if safe, you could use
> mmc_select_bus_width() in advance.
Ulf also questioned the requirment of doing this.
I consider droping this checking for the next version.
>
>> + if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
>> + err = mmc_compare_ext_csds(card, MMC_BUS_WIDTH_8);
>> + else
>> + err = mmc_bus_test(card, MMC_BUS_WIDTH_8);
>> +
>> + if (err) {
>> + pr_warn("%s: switch to enhanced strobe failed\n",
>> + mmc_hostname(host));
>> + return err;
>> + }
>> + }
>> +
>> if (!send_status) {
>> err = mmc_switch_status(card);
>> if (err)
>> @@ -1297,7 +1351,8 @@ err:
>> }
>>
>> /*
>> - * Activate High Speed or HS200 mode if supported.
>> + * Activate High Speed or HS200 mode if supported. For HS400
>> + * with enhanced strobe mode, we should activate High Speed.
>> */
>> static int mmc_select_timing(struct mmc_card *card)
>> {
>> @@ -1306,7 +1361,9 @@ static int mmc_select_timing(struct mmc_card *card)
>> if (!mmc_can_ext_csd(card))
>> goto bus_speed;
>>
>> - if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>> + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
>> + err = mmc_select_hs(card);
>
> In my view, you should just make a new function: mmc_select_hs400es()
I will spilt a new function to handle the hs400es timing slection.
>
>> + else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>> err = mmc_select_hs200(card);
>> else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
>> err = mmc_select_hs(card);
>> @@ -1578,7 +1635,15 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>> } else if (mmc_card_hs(card)) {
>> /* Select the desired bus width optionally */
>> err = mmc_select_bus_width(card);
>> - if (!IS_ERR_VALUE(err)) {
>> + if (IS_ERR_VALUE(err))
>> + goto free_card;
>> +
>> + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
>> + /* Directly from HS to HS400-ES */
>> + err = mmc_select_hs400(card);
>> + if (err)
>> + goto free_card;
>> + } else {
>> err = mmc_select_hs_ddr(card);
>> if (err)
>> goto free_card;
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index eb0151b..22defc2 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -95,6 +95,7 @@ struct mmc_ext_csd {
>> u8 raw_partition_support; /* 160 */
>> u8 raw_rpmb_size_mult; /* 168 */
>> u8 raw_erased_mem_count; /* 181 */
>> + u8 strobe_support; /* 184 */
>> u8 raw_ext_csd_structure; /* 194 */
>> u8 raw_card_type; /* 196 */
>> u8 raw_driver_strength; /* 197 */
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index 11e89d3..19de56c 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -19,6 +19,7 @@
>>
>> #include <linux/mmc/core.h>
>> #include <linux/mmc/card.h>
>> +#include <linux/mmc/mmc.h>
>> #include <linux/mmc/pm.h>
>>
>> struct mmc_ios {
>> @@ -143,6 +144,8 @@ struct mmc_host_ops {
>>
>> /* Prepare HS400 target operating frequency depending host driver */
>> int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
>> + /* Prepare enhanced strobe depending host driver */
>> + int (*prepare_enhanced_strobe)(struct mmc_host *host, bool enable);
>
> I don't see any need for an error return, so maybe make this return void.
> Also, we could put "bool enhanced_strobe" in struct mmc_ios and pass ios
> instead of enable.
yep, currently there's no need to check it.
I will change the name to hs400_enhacned_strobe as Ulf's suggestion,
and pass mmc_ios to this callback as well.
>
>> int (*select_drive_strength)(struct mmc_card *card,
>> unsigned int max_dtr, int host_drv,
>> int card_drv, int *drv_type);
>> @@ -518,6 +521,15 @@ static inline bool mmc_card_hs400(struct mmc_card *card)
>> return card->host->ios.timing == MMC_TIMING_MMC_HS400;
>> }
>>
>> +static inline bool mmc_card_hs400es(struct mmc_card *card)
>> +{
>> + if (mmc_card_hs400(card) &&
>> + (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES))
>> + return 1;
>
> We shouldn't assume that we are using it, just because it is available.
> How about putting "bool enhanced_strobe" in struct mmc_ios and checking that.
>
Good catch. Thanks.
>> +
>> + return 0;
>> +}
>> +
>> void mmc_retune_timer_stop(struct mmc_host *host);
>>
>> static inline void mmc_retune_needed(struct mmc_host *host)
>> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
>> index 15f2c4a..c376209 100644
>> --- a/include/linux/mmc/mmc.h
>> +++ b/include/linux/mmc/mmc.h
>> @@ -297,6 +297,7 @@ struct _mmc_csd {
>> #define EXT_CSD_PART_CONFIG 179 /* R/W */
>> #define EXT_CSD_ERASED_MEM_CONT 181 /* RO */
>> #define EXT_CSD_BUS_WIDTH 183 /* R/W */
>> +#define EXT_CSD_STROBE_SUPPORT 184 /* RO */
>> #define EXT_CSD_HS_TIMING 185 /* R/W */
>> #define EXT_CSD_POWER_CLASS 187 /* R/W */
>> #define EXT_CSD_REV 192 /* RO */
>> @@ -380,12 +381,14 @@ struct _mmc_csd {
>> #define EXT_CSD_CARD_TYPE_HS400_1_2V (1<<7) /* Card can run at 200MHz DDR, 1.2V */
>> #define EXT_CSD_CARD_TYPE_HS400 (EXT_CSD_CARD_TYPE_HS400_1_8V | \
>> EXT_CSD_CARD_TYPE_HS400_1_2V)
>> +#define EXT_CSD_CARD_TYPE_HS400ES (1<<8) /* Card can run at HS400ES */
>>
>> #define EXT_CSD_BUS_WIDTH_1 0 /* Card is in 1 bit mode */
>> #define EXT_CSD_BUS_WIDTH_4 1 /* Card is in 4 bit mode */
>> #define EXT_CSD_BUS_WIDTH_8 2 /* Card is in 8 bit mode */
>> #define EXT_CSD_DDR_BUS_WIDTH_4 5 /* Card is in 4 bit DDR mode */
>> #define EXT_CSD_DDR_BUS_WIDTH_8 6 /* Card is in 8 bit DDR mode */
>> +#define EXT_CSD_BUS_WIDTH_STROBE BIT(7) /* Enhanced strobe mode */
>>
>> #define EXT_CSD_TIMING_BC 0 /* Backwards compatility */
>> #define EXT_CSD_TIMING_HS 1 /* High speed */
>>
>
>
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