Re: [PATCH V1] mmc: core: Add partial initialization support

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On 6/2/2022 1:26 PM, Ben Chuang wrote:
Hi Sarthak and others,

I like your patch, I'm not familiar with the whole sleep/wake flow.
But I have a question.

Regarding mmc_poweroff_notify() , there is a parameter notify_type.
In the spec., it has a value 0x04: SLEEP_NOTIFICATION (host is going
to put the device in sleep mode.)
Is there anything that needs to be changed in _mmc_suspend() before
calling mmc_sleepawake(host, true)/mmc_power_off(host)?
Thanks in advance.

Best regards,
Ben


Hi Ben,

I went through the sleep notification in the eMMC spec. This sleep notification seems optional as per this statement in spec: "It *may* use to a power notification (SLEEP_NOTIFICATION) if it intends to turn-off VCC after moving the device to sleep state". So it doesn't seem to be a good club this with my change. We can revisit and take this separately.

Thanks,
Sarthak


On Wed, May 25, 2022 at 12:31 AM Kamasali Satyanarayan (Consultant)
(QUIC) <quic_kamasali@xxxxxxxxxxx> wrote:
Hi,

These patches will be further taken by Sarthak.

Thanks,
Satya

-----Original Message-----
From: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Sent: Wednesday, April 27, 2022 1:06 PM
To: quic_spathi <quic_spathi@xxxxxxxxxxx>
Cc: avri.altman@xxxxxxx; linus.walleij@xxxxxxxxxx; shawn.lin@xxxxxxxxxxxxxx; merez@xxxxxxxxxxxxxx; s.shtylyov@xxxxxx; huijin.park@xxxxxxxxxxx; briannorris@xxxxxxxxxxxx; digetx@xxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>; Shaik Sajida Bhanu <sbhanu@xxxxxxxxxxxxxx>; Kamasali Satyanarayan (Consultant) (QUIC) <quic_kamasali@xxxxxxxxxxx>
Subject: Re: [PATCH V1] mmc: core: Add partial initialization support

On Tue, 26 Apr 2022 at 11:04, Srinivasarao Pathipati <quic_spathi@xxxxxxxxxxx> wrote:
From: Maya Erez <merez@xxxxxxxxxxxxxx>

This change adds the ability to partially initialize the MMC card by
using card Sleep/Awake sequence (CMD5).
Card will be sent to Sleep state during runtime/system suspend and
will be woken up during runtime/system resume.
By using this sequence the card doesn't need full initialization which
gives time reduction in system/runtime resume path.

Signed-off-by: Maya Erez <merez@xxxxxxxxxxxxxx>
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>
Signed-off-by: Shaik Sajida Bhanu <sbhanu@xxxxxxxxxxxxxx>
Signed-off-by: kamasali <quic_kamasali@xxxxxxxxxxx>
Signed-off-by: Srinivasarao Pathipati <quic_spathi@xxxxxxxxxxx>
It seems like this patch has been posted before [1]. Let me repeat my question sent back then.

It would be nice if you could provide some more exact numbers of what the gain is for a couple of different eMMCs, to justify the change.
Can you please do that?

Kind regards
Uffe

[1]
https://patchwork.kernel.org/project/linux-mmc/patch/1591277381-7734-1-git-send-email-vbadigan@xxxxxxxxxxxxxx/

---
  drivers/mmc/core/mmc.c   | 149 ++++++++++++++++++++++++++++++++++++++++++++---
  include/linux/mmc/card.h |   4 ++
  include/linux/mmc/host.h |   2 +
  3 files changed, 146 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
9ab915b..8691c00 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1942,7 +1942,14 @@ static int mmc_sleep_busy_cb(void *cb_data, bool *busy)
         return 0;
  }

-static int mmc_sleep(struct mmc_host *host)
+static int mmc_can_sleepawake(struct mmc_host *host) {
+       return host && (host->caps2 & MMC_CAP2_SLEEP_AWAKE) && host->card &&
+               (host->card->ext_csd.rev >= 3);
+
+}
+
+static int mmc_sleepawake(struct mmc_host *host, bool sleep)
  {
         struct mmc_command cmd = {};
         struct mmc_card *card = host->card; @@ -1953,14 +1960,17 @@
static int mmc_sleep(struct mmc_host *host)
         /* Re-tuning can't be done once the card is deselected */
         mmc_retune_hold(host);

-       err = mmc_deselect_cards(host);
-       if (err)
-               goto out_release;
+       if (sleep) {
+               err = mmc_deselect_cards(host);
+               if (err)
+                       goto out_release;
+       }

         cmd.opcode = MMC_SLEEP_AWAKE;
         cmd.arg = card->rca << 16;
-       cmd.arg |= 1 << 15;
         use_r1b_resp = mmc_prepare_busy_cmd(host, &cmd, timeout_ms);
+       if (sleep)
+               cmd.arg |= 1 << 15;

         err = mmc_wait_for_cmd(host, &cmd, 0);
         if (err)
@@ -1982,6 +1992,9 @@ static int mmc_sleep(struct mmc_host *host)

         err = __mmc_poll_for_busy(host, 0, timeout_ms,
&mmc_sleep_busy_cb, host);

+       if (!sleep)
+               err = mmc_select_card(card);
+
  out_release:
         mmc_retune_release(host);
         return err;
@@ -2080,6 +2093,66 @@ static int _mmc_flush_cache(struct mmc_host *host)
                         pr_err("%s: cache flush error %d\n",
                                mmc_hostname(host), err);
         }
+       return err;
+}
+
+static int mmc_cache_card_ext_csd(struct mmc_host *host) {
+       int err;
+       u8 *ext_csd;
+       struct mmc_card *card = host->card;
+
+       err = mmc_get_ext_csd(card, &ext_csd);
+       if (err || !ext_csd) {
+               pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
+                       mmc_hostname(host), __func__, err);
+               return err;
+       }
+       /* only cache read/write fields that the sw changes */
+       card->ext_csd.raw_ext_csd_cmdq = ext_csd[EXT_CSD_CMDQ_MODE_EN];
+       card->ext_csd.raw_ext_csd_cache_ctrl = ext_csd[EXT_CSD_CACHE_CTRL];
+       card->ext_csd.raw_ext_csd_bus_width = ext_csd[EXT_CSD_BUS_WIDTH];
+       card->ext_csd.raw_ext_csd_hs_timing =
+ ext_csd[EXT_CSD_HS_TIMING];
+
+       kfree(ext_csd);
+
+       return 0;
+}
+
+static int mmc_test_awake_ext_csd(struct mmc_host *host) {
+       int err;
+       u8 *ext_csd;
+       struct mmc_card *card = host->card;
+
+       err = mmc_get_ext_csd(card, &ext_csd);
+       if (err) {
+               pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
+                       mmc_hostname(host), __func__, err);
+               return err;
+       }
+
+       /* only compare read/write fields that the sw changes */
+       pr_debug("%s: %s: type(cached:current) cmdq(%d:%d) cache_ctrl(%d:%d) bus_width (%d:%d) timing(%d:%d)\n",
+               mmc_hostname(host), __func__,
+               card->ext_csd.raw_ext_csd_cmdq,
+               ext_csd[EXT_CSD_CMDQ_MODE_EN],
+               card->ext_csd.raw_ext_csd_cache_ctrl,
+               ext_csd[EXT_CSD_CACHE_CTRL],
+               card->ext_csd.raw_ext_csd_bus_width,
+               ext_csd[EXT_CSD_BUS_WIDTH],
+               card->ext_csd.raw_ext_csd_hs_timing,
+               ext_csd[EXT_CSD_HS_TIMING]);
+       err = !((card->ext_csd.raw_ext_csd_cmdq ==
+                       ext_csd[EXT_CSD_CMDQ_MODE_EN]) &&
+               (card->ext_csd.raw_ext_csd_cache_ctrl ==
+                       ext_csd[EXT_CSD_CACHE_CTRL]) &&
+               (card->ext_csd.raw_ext_csd_bus_width ==
+                       ext_csd[EXT_CSD_BUS_WIDTH]) &&
+               (card->ext_csd.raw_ext_csd_hs_timing ==
+                       ext_csd[EXT_CSD_HS_TIMING]));
+
+       kfree(ext_csd);

         return err;
  }
@@ -2103,8 +2176,12 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
             ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend ||
              (host->caps2 & MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND)))
                 err = mmc_poweroff_notify(host->card, notify_type);
-       else if (mmc_can_sleep(host->card))
-               err = mmc_sleep(host);
+       if (mmc_can_sleepawake(host)) {
+               memcpy(&host->cached_ios, &host->ios, sizeof(host->cached_ios));
+                mmc_cache_card_ext_csd(host);
+       }
+       if (mmc_can_sleep(host->card))
+               err = mmc_sleepawake(host, true);
         else if (!mmc_host_is_spi(host))
                 err = mmc_deselect_cards(host);

@@ -2117,6 +2194,48 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
         return err;
  }

+static int mmc_partial_init(struct mmc_host *host) {
+       int err = 0;
+       struct mmc_card *card = host->card;
+
+       mmc_set_bus_width(host, host->cached_ios.bus_width);
+       mmc_set_timing(host, host->cached_ios.timing);
+       if (host->cached_ios.enhanced_strobe) {
+               host->ios.enhanced_strobe = true;
+               if (host->ops->hs400_enhanced_strobe)
+                       host->ops->hs400_enhanced_strobe(host, &host->ios);
+       }
+       mmc_set_clock(host, host->cached_ios.clock);
+       mmc_set_bus_mode(host, host->cached_ios.bus_mode);
+
+       if (!mmc_card_hs400es(card) &&
+                       (mmc_card_hs200(card) || mmc_card_hs400(card))) {
+               err = mmc_execute_tuning(card);
+               if (err) {
+                       pr_err("%s: %s: Tuning failed (%d)\n",
+                               mmc_hostname(host), __func__, err);
+                       goto out;
+               }
+       }
+       /*
+        * The ext_csd is read to make sure the card did not went through
+        * Power-failure during sleep period.
+        * A subset of the W/E_P, W/C_P register will be tested. In case
+        * these registers values are different from the values that were
+        * cached during suspend, we will conclude that a Power-failure occurred
+        * and will do full initialization sequence.
+        */
+       err = mmc_test_awake_ext_csd(host);
+       if (err) {
+               pr_debug("%s: %s: fail on ext_csd read (%d)\n",
+                       mmc_hostname(host), __func__, err);
+               goto out;
+       }
+out:
+       return err;
+}
+
  /*
   * Suspend callback
   */
@@ -2139,7 +2258,7 @@ static int mmc_suspend(struct mmc_host *host)
   */
  static int _mmc_resume(struct mmc_host *host)  {
-       int err = 0;
+       int err = -EINVAL;

         mmc_claim_host(host);

@@ -2147,7 +2266,19 @@ static int _mmc_resume(struct mmc_host *host)
                 goto out;

         mmc_power_up(host, host->card->ocr);
-       err = mmc_init_card(host, host->card->ocr, host->card);
+
+       if (mmc_can_sleepawake(host)) {
+               err = mmc_sleepawake(host, false);
+               if (!err)
+                       err = mmc_partial_init(host);
+               else
+                       pr_err("%s: %s: awake failed (%d), fallback to full init\n",
+                               mmc_hostname(host), __func__, err);
+       }
+
+       if (err)
+               err = mmc_init_card(host, host->card->ocr, host->card);
+
         mmc_card_clr_suspended(host->card);

  out:
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 37f9758..ed7f6f7 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -86,6 +86,8 @@ struct mmc_ext_csd {
         unsigned int            data_tag_unit_size;     /* DATA TAG UNIT size */
         unsigned int            boot_ro_lock;           /* ro lock support */
         bool                    boot_ro_lockable;
+       u8                      raw_ext_csd_cmdq;       /* 15 */
+       u8                      raw_ext_csd_cache_ctrl; /* 33 */
         bool                    ffu_capable;    /* Firmware upgrade support */
         bool                    cmdq_en;        /* Command Queue enabled */
         bool                    cmdq_support;   /* Command Queue supported */
@@ -96,7 +98,9 @@ struct mmc_ext_csd {
         u8                      raw_partition_support;  /* 160 */
         u8                      raw_rpmb_size_mult;     /* 168 */
         u8                      raw_erased_mem_count;   /* 181 */
+       u8                      raw_ext_csd_bus_width;  /* 183 */
         u8                      strobe_support;         /* 184 */
+       u8                      raw_ext_csd_hs_timing;  /* 185 */
         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 c38072e..a9ddf7a 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -422,6 +422,7 @@ struct mmc_host {
  #else
  #define MMC_CAP2_CRYPTO                0
  #endif
+#define MMC_CAP2_SLEEP_AWAKE   (1 << 29)       /* Use Sleep/Awake (CMD5) */
  #define MMC_CAP2_ALT_GPT_TEGRA (1 << 28)       /* Host with eMMC that has GPT entry at a non-standard location */

         int                     fixed_drv_type; /* fixed driver type for non-removable media */
@@ -441,6 +442,7 @@ struct mmc_host {
         spinlock_t              lock;           /* lock for claim and bus ops */

         struct mmc_ios          ios;            /* current io bus settings */
+       struct mmc_ios          cached_ios;

         /* group bitfields together to minimize padding */
         unsigned int            use_spi_crc:1;
--
2.7.4




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