Re: [PATCH v3 1/2] MMC-4.5 Power OFF Notify rework

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Hi Girish,

Please some comments below.

On 05/11/2012 01:44 PM, Subhash Jadavani wrote:
Hi Girish,

On 5/7/2012 7:11 PM, Girish K S wrote:
This is a rework of the existing POWER OFF NOTIFY patch. The current problem
with the patch comes from the ambiguity on the usage of POWER OFF NOTIFY
together with SLEEP and misunderstanding on the usage of MMC_POWER_OFF
power_mode from mmc_set_ios in different host controller drivers.

This new patch works around this problem by adding a new host CAP,
MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND, which when set sends a
POWER OFF NOTIFY from mmc_suspend instead of SLEEP. It is expected that host
controller drivers will set this CAP, if they switch off both Vcc and Vccq
from MMC_POWER_OFF condition within mmc_set_ios. However, note that there
is no harm in sending MMC_POWER_NOTIFY even if Vccq is not switched off.

This patch also sends POWER OFF NOTIFY from power management routines (e.g.
mmc_power_save_host, mmc_pm_notify/PM_SUSPEND_PREPARE, mmc_stop_host), which
does reinitialization of the eMMC on the return path of the power management
routines (e.g. mmc_power_restore_host, mmc_pm_notify/PM_POST_RESTORE,
mmc_start_host).

This patch sets POWER_OFF_NOTIFICATION to POWER_OFF_SHORT if it is sent from
the suspend sequence. If it is sent from shutdown sequence then it is set to
POWER_OFF_LONG.

Previuos implementation of PowerOff Notify as a core function is replaced as
a device's bus operation.

Signed-off-by: Saugata Das<saugata.das@xxxxxxxxxx>
Signed-off-by: Girish K S<girish.shivananjappa@xxxxxxxxxx>

changes in v3:
       This version addresses the review comments given by Subhash and Ulf
changes in v2:
       This version addresses the changes suggested by Ulf
---
   drivers/mmc/core/core.c  |   98 +++++++++++++++-------------------------------
   drivers/mmc/core/core.h  |    1 +
   drivers/mmc/core/mmc.c   |   73 ++++++++++++++++++++++++++++------
   include/linux/mmc/card.h |    8 +++-
   include/linux/mmc/host.h |    9 ++--
   5 files changed, 105 insertions(+), 84 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ba821fe..3db3b32 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1100,48 +1100,6 @@ void mmc_set_driver_type(struct mmc_host *host, unsigned int drv_type)
       mmc_host_clk_release(host);
   }

-static void mmc_poweroff_notify(struct mmc_host *host)
-{
-     struct mmc_card *card;
-     unsigned int timeout;
-     unsigned int notify_type = EXT_CSD_NO_POWER_NOTIFICATION;
-     int err = 0;
-
-     card = host->card;
-     mmc_claim_host(host);
-
-     /*
-      * Send power notify command only if card
-      * is mmc and notify state is powered ON
-      */
-     if (card&&   mmc_card_mmc(card)&&
-         (card->poweroff_notify_state == MMC_POWERED_ON)) {
-
-             if (host->power_notify_type == MMC_HOST_PW_NOTIFY_SHORT) {
-                     notify_type = EXT_CSD_POWER_OFF_SHORT;
-                     timeout = card->ext_csd.generic_cmd6_time;
-                     card->poweroff_notify_state = MMC_POWEROFF_SHORT;
-             } else {
-                     notify_type = EXT_CSD_POWER_OFF_LONG;
-                     timeout = card->ext_csd.power_off_longtime;
-                     card->poweroff_notify_state = MMC_POWEROFF_LONG;
-             }
-
-             err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
-                              EXT_CSD_POWER_OFF_NOTIFICATION,
-                              notify_type, timeout);
-
-             if (err&&   err != -EBADMSG)
-                     pr_err("Device failed to respond within %d poweroff "
-                            "time. Forcefully powering down the device\n",
-                            timeout);
-
-             /* Set the card state to no notification after the poweroff */
-             card->poweroff_notify_state = MMC_NO_POWER_NOTIFICATION;
-     }
-     mmc_release_host(host);
-}
-
   /*
    * Apply power to the MMC stack.  This is a two-stage process.
    * First, we enable power to the card without the clock running.
@@ -1198,30 +1156,12 @@ static void mmc_power_up(struct mmc_host *host)

   void mmc_power_off(struct mmc_host *host)
   {
-     int err = 0;
       mmc_host_clk_hold(host);

       host->ios.clock = 0;
       host->ios.vdd = 0;

       /*
-      * For eMMC 4.5 device send AWAKE command before
-      * POWER_OFF_NOTIFY command, because in sleep state
-      * eMMC 4.5 devices respond to only RESET and AWAKE cmd
-      */
-     if (host->card&&   mmc_card_is_sleep(host->card)&&
-         host->bus_ops->resume) {
-             err = host->bus_ops->resume(host);
-
-             if (!err)
-                     mmc_poweroff_notify(host);
-             else
-                     pr_warning("%s: error %d during resume "
-                                "(continue with poweroff sequence)\n",
-                                mmc_hostname(host), err);
-     }
-
-     /*
        * Reset ocr mask to be the highest possible voltage supported for
        * this mmc host. This value will be used at next power up.
        */
@@ -2081,9 +2021,16 @@ void mmc_stop_host(struct mmc_host *host)

       /* clear pm flags now and let card drivers set them as needed */
       host->pm_flags = 0;
-
       mmc_bus_get(host);
       if (host->bus_ops&&   !host->bus_dead) {
+
+             if (host->bus_ops->poweroff_notify) {

Instead of checking EOPNOTSUP you can do:
if (mmc_card_can_poweroff_notify ..)


+                     int err = host->bus_ops->poweroff_notify(host);
+                     if (err&&   err != -EOPNOTSUPP)
+                             pr_info("%s: error [%d] in poweroff notify\n",
+                                     mmc_hostname(host), err);
+             }
+
               /* Calling bus_ops->remove() with a claimed host can deadlock */
               if (host->bus_ops->remove)
                       host->bus_ops->remove(host);
@@ -2093,6 +2040,7 @@ void mmc_stop_host(struct mmc_host *host)
               mmc_power_off(host);
               mmc_release_host(host);
               mmc_bus_put(host);
+

white space

               return;
       }
       mmc_bus_put(host);
@@ -2119,6 +2067,13 @@ int mmc_power_save_host(struct mmc_host *host)

       if (host->bus_ops->power_save)
               ret = host->bus_ops->power_save(host);
+     host->poweroff_notify_type = MMC_HOST_PW_OFF_NOTIFY_SHORT;
Before sending this short power off notification, shouldn't we make sure
that host has defined MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND cap?

Instead of checking EOPNOTSUP you can do:
if (mmc_card_can_poweroff_notify ..)

Moreover MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND shall be checked during mmc_init_card, when setting poweroff_notify_state to MMC_POWERED_ON, that is not done today.

Thereafter you can only do this when checking if poweroff_notify shall be done:
"if (mmc_card_can_poweroff_notify ..)"

+     if (host->bus_ops->poweroff_notify) {
+             int err = host->bus_ops->poweroff_notify(host);
+             if (err&&   err != -EOPNOTSUPP)
+                     pr_info("%s: error [%d] in poweroff notify\n",
+                             mmc_hostname(host), err);
+     }

       mmc_bus_put(host);

@@ -2142,7 +2097,6 @@ int mmc_power_restore_host(struct mmc_host *host)
               mmc_bus_put(host);
               return -EINVAL;
       }
-
       mmc_power_up(host);
       ret = host->bus_ops->power_restore(host);

@@ -2161,8 +2115,11 @@ int mmc_card_awake(struct mmc_host *host)

       mmc_bus_get(host);

-     if (host->bus_ops&&   !host->bus_dead&&   host->bus_ops->awake)
+     if (host->bus_ops&&   !host->bus_dead&&   host->bus_ops->awake) {
               err = host->bus_ops->awake(host);
+             if (!err)
+                     mmc_card_clr_sleep(host->card);
+     }

       mmc_bus_put(host);

@@ -2179,8 +2136,11 @@ int mmc_card_sleep(struct mmc_host *host)

       mmc_bus_get(host);

-     if (host->bus_ops&&   !host->bus_dead&&   host->bus_ops->sleep)
+     if (host->bus_ops&&   !host->bus_dead&&   host->bus_ops->sleep) {
               err = host->bus_ops->sleep(host);
+             if (!err)
+                     mmc_card_set_sleep(host->card);
+     }

       mmc_bus_put(host);

@@ -2373,12 +2333,18 @@ int mmc_pm_notify(struct notifier_block *notify_block,

               spin_lock_irqsave(&host->lock, flags);
               host->rescan_disable = 1;
-             host->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
+             host->poweroff_notify_type = MMC_HOST_PW_OFF_NOTIFY_SHORT;
Before sending this short power off notification, shouldn't we make sure
that host has defined MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND cap?
Suggest to remove the "poweroff_notify_type" variable in the host. Use an in-parameter to the poweroff_notify bus_ops function instead.

               spin_unlock_irqrestore(&host->lock, flags);
               cancel_delayed_work_sync(&host->detect);

               if (!host->bus_ops || host->bus_ops->suspend)
                       break;

You can do this instead:
"if (mmc_card_can_poweroff_notify ..)"
+             if (host->bus_ops->poweroff_notify) {
+                     int err = host->bus_ops->poweroff_notify(host);
+                     if (err&&   err != -EOPNOTSUPP)
+                             pr_info("%s: error [%d] in poweroff notify\n",
+                                     mmc_hostname(host), err);
+             }

               /* Calling bus_ops->remove() with a claimed host can deadlock */
               if (host->bus_ops->remove)
@@ -2397,7 +2363,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,

               spin_lock_irqsave(&host->lock, flags);
               host->rescan_disable = 0;
-             host->power_notify_type = MMC_HOST_PW_NOTIFY_LONG;
+             host->poweroff_notify_type = MMC_HOST_PW_OFF_NOTIFY_LONG;

Suggest to remove the "poweroff_notify_type" variable in the host. Use an in-parameter to the poweroff_notify bus_ops function instead.

               spin_unlock_irqrestore(&host->lock, flags);
               mmc_detect_change(host, 0);

diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 3bdafbc..351cbbe 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -25,6 +25,7 @@ struct mmc_bus_ops {
       int (*power_save)(struct mmc_host *);
       int (*power_restore)(struct mmc_host *);
       int (*alive)(struct mmc_host *);
+     int (*poweroff_notify)(struct mmc_host *);
   };

   void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 54df5ad..a86e5f8 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1282,6 +1282,47 @@ err:
       return err;
   }

+static int mmc_poweroff_notify(struct mmc_host *host)

Suggest to add a "poweroff_notify_type" as in-parameter instead of using the host struct for storing this information.

+{
+     struct mmc_card *card;
+     unsigned int timeout;
+     unsigned int notify_type = EXT_CSD_NO_POWER_NOTIFICATION;
+     int err = -EOPNOTSUPP;
+
+     card = host->card;
+
+     /*
+      * Send power notify command only if card
+      * is mmc and notify state is powered ON
+      */
+     if (mmc_card_can_poweroff_notify(host->card)) {

Suggest to move this check outside of this function. Please see how this is done for mmc_card_can_sleep and mmc_card_sleep.

+             if (host->poweroff_notify_type ==
+                                     MMC_HOST_PW_OFF_NOTIFY_SHORT) {
+                     notify_type = EXT_CSD_POWER_OFF_SHORT;
+                     timeout = card->ext_csd.generic_cmd6_time;
+             } else {
poweroff_notify_type can take 3 different values.
          #define MMC_HOST_PW_OFF_NOTIFY_NONE             0
          #define MMC_HOST_PW_OFF_NOTIFY_SHORT            1
          #define MMC_HOST_PW_OFF_NOTIFY_LONG             2

So shouldn't we have explicit check for NOTIFY_LONG?
          else if (notify_type == LONG) { ... }
          else {error printing?}

+                     notify_type = EXT_CSD_POWER_OFF_LONG;
+                     timeout = card->ext_csd.power_off_longtime;
+             }
+
+             mmc_claim_host(host);

Suggest to handle claim and release outside this function. Similar how mmc_card_sleep is implemented.

+             err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                              EXT_CSD_POWER_OFF_NOTIFICATION,
+                              notify_type, timeout);
+             mmc_release_host(host);
+
+             if (err&&   err != -EBADMSG)
+                     pr_err("%s: Device failed to respond within %d "
+                            "poweroff time. Forcefully powering down "
+                            "the device\n", mmc_hostname(host), timeout);
+             else
+                     card->poweroff_notify_state =
+                                             MMC_NO_POWER_NOTIFICATION;
Just wondering, if we should really to set the notify_state to
NO_POWER_NOTIFICATION incase if err = -EBADMSG ?
+     }
+
+     return err;
+}
+
   /*
    * Host is being removed. Free up the current card.
    */
@@ -1341,15 +1382,21 @@ static int mmc_suspend(struct mmc_host *host)
       BUG_ON(!host);
       BUG_ON(!host->card);

-     mmc_claim_host(host);

Suggest to handle claim and release as before and not inside the mmc_poweroff_notify function. Similar how mmc_card_sleep is implemented.

-     if (mmc_card_can_sleep(host)) {
-             err = mmc_card_sleep(host);
-             if (!err)
-                     mmc_card_set_sleep(host->card);
-     } else if (!mmc_host_is_spi(host))
-             mmc_deselect_cards(host);
-     host->card->state&= ~(MMC_STATE_HIGHSPEED | MMC_STATE_HIGHSPEED_200);
-     mmc_release_host(host);
+     if (mmc_card_can_poweroff_notify(host->card)&&
+             (host->caps2&   MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND)) {
Sorry for not proposing this earlier;
By checking the MMC_CAP2_POWER_OFF_VCCQ_DURING_SUSPEND could be done only from mmc_init_card function, it is enough to check "mmc_card_can_poweroff_notify".

+             err = mmc_poweroff_notify(host);
+     } else {
+             mmc_claim_host(host);
+             if (mmc_card_can_sleep(host))
+                     err = mmc_card_sleep(host);
+             else if (!mmc_host_is_spi(host))
+                     mmc_deselect_cards(host);
+             mmc_release_host(host);
+     }
+
+     if (!err)
+             host->card->state&=
+                     ~(MMC_STATE_HIGHSPEED | MMC_STATE_HIGHSPEED_200);

       return err;
   }
@@ -1368,11 +1415,11 @@ static int mmc_resume(struct mmc_host *host)
       BUG_ON(!host->card);

       mmc_claim_host(host);
-     if (mmc_card_is_sleep(host->card)) {
+     if (mmc_card_is_sleep(host->card))
               err = mmc_card_awake(host);
-             mmc_card_clr_sleep(host->card);
-     } else
+     else
               err = mmc_init_card(host, host->ocr, host->card);
+
       mmc_release_host(host);

       return err;
@@ -1430,6 +1477,7 @@ static const struct mmc_bus_ops mmc_ops = {
       .resume = NULL,
       .power_restore = mmc_power_restore,
       .alive = mmc_alive,
+     .poweroff_notify = mmc_poweroff_notify,
   };

   static const struct mmc_bus_ops mmc_ops_unsafe = {
@@ -1441,6 +1489,7 @@ static const struct mmc_bus_ops mmc_ops_unsafe = {
       .resume = mmc_resume,
       .power_restore = mmc_power_restore,
       .alive = mmc_alive,
+     .poweroff_notify = mmc_poweroff_notify,
   };

   static void mmc_attach_bus_ops(struct mmc_host *host)
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 629b823..a6cdc43 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -238,8 +238,6 @@ struct mmc_card {
       unsigned int    poweroff_notify_state;  /* eMMC4.5 notify feature */
   #define MMC_NO_POWER_NOTIFICATION   0
   #define MMC_POWERED_ON                      1
-#define MMC_POWEROFF_SHORT           2
-#define MMC_POWEROFF_LONG            3

       unsigned int            erase_size;     /* erase size in sectors */
       unsigned int            erase_shift;    /* if erase unit is power 2 */
@@ -465,6 +463,12 @@ static inline int mmc_card_long_read_time(const struct mmc_card *c)
       return c->quirks&   MMC_QUIRK_LONG_READ_TIME;
   }

+static inline int mmc_card_can_poweroff_notify(const struct mmc_card *c)
+{
+     return c&&   mmc_card_mmc(c)&&
+                             (c->poweroff_notify_state == MMC_POWERED_ON);
+}
+
I guess you may want to move this function in drivers/mmc/core/core.c
along with other mmc_can_* function in same file. Look for
mmc_can_sanitize() or mmc_can_discard() functions as example.

   #define mmc_card_name(c)    ((c)->cid.prod_name)
   #define mmc_card_id(c)              (dev_name(&(c)->dev))

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 0707d22..aad894e 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -238,12 +238,13 @@ 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_POWER_OFF_VCCQ_DURING_SUSPEND       (1<<   10)

       mmc_pm_flag_t           pm_caps;        /* supported pm features */
-     unsigned int        power_notify_type;
-#define MMC_HOST_PW_NOTIFY_NONE              0
-#define MMC_HOST_PW_NOTIFY_SHORT     1
-#define MMC_HOST_PW_NOTIFY_LONG              2

Suggest to remove this entirely from the mmc host struct.

+     unsigned int        poweroff_notify_type;
Can you add additional tab to make poweroff_notify_state aligned to
other members in this same structure?
+#define MMC_HOST_PW_OFF_NOTIFY_NONE          0
+#define MMC_HOST_PW_OFF_NOTIFY_SHORT         1
+#define MMC_HOST_PW_OFF_NOTIFY_LONG          2

   #ifdef CONFIG_MMC_CLKGATE
       int                     clk_requests;   /* internal reference counter */


Kind regards
Ulf Hansson
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