Re: [PATCH v4] mmc: core: select the operation mode with sysfs

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi Mr.Jeon.

On 02/06/2012 01:19 PM, Namjae Jeon wrote:

> Hi. Jaehoon.
> 
> I have questions.
> 
> 1. Would you explain why we need on/off function of this CMD23 at runtime ?

Now..operation mode is set at compile time..That means if we use the pre-defined mode,
must always use the pre-defined mode.
Packed-cmd, Data-tag, Context-Id..etc..almost features need to use CMD23.
But in vendor side, some card need to use the open-ended in order to update the firmware code.
(or not)
If we use the cmd23, to update the firmware code maybe need to rebuild..it's worthless.
So i added this patch.

> 2. While frequently reading/writing, Have you tested by being
> enabling/disbling CMD23 using this function ?

Yes..i tested that case..and working well.

> 3. Why is irq disable needed when calling mmc_change_operation_mode ?
> If are we just using spin_lock ?

that value is how we process the request, so i think that need spin_lock_irq().
Well..spin_lock()? i think that..

> 4. When do we use host->pre_defined_op value after setting it ?

Just the setting value..to show the value..any other opinion.
If you have the other approach, i will change.

Best Regards,
Jaehoon Chung

> 
> Thanks.
> 
> 2012/2/6 Jaehoon Chung <jh80.chung@samsung.com>:
>> This patch is support the sysfs for operation mode.
>>
>> There are two operation modes(open-ended/pre-defined).
>> Now, operation mode is selected only one at the compile time.
>>
>> But using this patch, we can change the operation mode with node at runtime.
>>
>> * pre-defined mode
>> echo 1 > /sys/class/mmc_host/mmc0/pre_defined_op
>> * open-ended mode
>> echo 0 > /sys/class/mmc_host/mmc0/pre_defined_op
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>> ---
>> Changelog V4:
>>        - Add the explanation in Documentation/mmc/mmc-dev-attrs.txt
>> Changelog V3:
>>        - Add the mmc_change_operation_mode()
>> Changelog v2:
>>        - Add the check point in mmc_cmd23_store()
>>        (If host controller didn't support CMD23, need not to change the ops-mode.)
>>
>>  Documentation/mmc/mmc-dev-attrs.txt |   16 ++++++++++++++
>>  drivers/mmc/card/block.c            |   19 +++++++++++++++++
>>  drivers/mmc/core/host.c             |   39 +++++++++++++++++++++++++++++++++++
>>  include/linux/mmc/card.h            |    1 +
>>  include/linux/mmc/host.h            |    3 ++
>>  5 files changed, 78 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/mmc/mmc-dev-attrs.txt b/Documentation/mmc/mmc-dev-attrs.txt
>> index 22ae844..e7ba3b6 100644
>> --- a/Documentation/mmc/mmc-dev-attrs.txt
>> +++ b/Documentation/mmc/mmc-dev-attrs.txt
>> @@ -74,3 +74,19 @@ This attribute appears only if CONFIG_MMC_CLKGATE is enabled.
>>        clkgate_delay   Tune the clock gating delay with desired value in milliseconds.
>>
>>  echo <desired delay> > /sys/class/mmc_host/mmcX/clkgate_delay
>> +
>> +SD and MMC Operation Mode Attribute
>> +==========================================
>> +
>> +SD and MMC can support the two operation mode.
>> +(Pre-defined(CMD23)/Open-ended operation mode)
>> +
>> +This attribute can change the operation mode at runtime if card is supported the CMD23.
>> +
>> +       pre_defined_op  Support the pre-defined mode if set 1.
>> +
>> +1) Open-ended mode
>> +echo 0 > /sys/class/mmc_host/mmcX/pre_defined_op
>> +
>> +2) Pre-defined mode
>> +echo 1 > /sys/class/mmc_host/mmcX/pre_defined_op
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index a7c75d8..2c1981c 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -1766,6 +1766,25 @@ static const struct mmc_fixup blk_fixups[] =
>>        END_FIXUP
>>  };
>>
>> +void mmc_change_operation_mode(struct mmc_card *card, int val)
>> +{
>> +       struct mmc_blk_data *md = mmc_get_drvdata(card);
>> +
>> +       if (mmc_host_cmd23(card->host)) {
>> +               if (mmc_card_mmc(card) ||
>> +                   (mmc_card_sd(card) &&
>> +                    card->scr.cmds & SD_SCR_CMD23_SUPPORT)) {
>> +                       if (val) {
>> +                               md->flags |= MMC_BLK_CMD23;
>> +                               card->host->pre_defined_op = val;
>> +                       } else {
>> +                               md->flags &= ~MMC_BLK_CMD23;
>> +                               card->host->pre_defined_op = val;
>> +                       }
>> +               }
>> +       }
>> +}
>> +
>>  static int mmc_blk_probe(struct mmc_card *card)
>>  {
>>        struct mmc_blk_data *md, *part_md;
>> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
>> index 30055f2..7dab0dc 100644
>> --- a/drivers/mmc/core/host.c
>> +++ b/drivers/mmc/core/host.c
>> @@ -293,6 +293,41 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
>>
>>  #endif
>>
>> +static ssize_t mmc_cmd23_show(struct device *dev,
>> +               struct device_attribute *attr, char *buf)
>> +{
>> +       struct mmc_host *host = cls_dev_to_mmc_host(dev);
>> +       return snprintf(buf, PAGE_SIZE, "%d\n", host->pre_defined_op);
>> +}
>> +
>> +static ssize_t mmc_cmd23_store(struct device *dev,
>> +               struct device_attribute *attr, const char *buf, size_t count)
>> +{
>> +       struct mmc_host *host = cls_dev_to_mmc_host(dev);
>> +       int value;
>> +       unsigned long flags;
>> +
>> +       if (kstrtoint(buf, 0, &value))
>> +               return -EINVAL;
>> +
>> +       spin_lock_irqsave(&host->lock, flags);
>> +       mmc_change_operation_mode(host->card, value);
>> +       spin_unlock_irqrestore(&host->lock, flags);
>> +       return count;
>> +}
>> +
>> +static inline void mmc_host_cmd23_sysfs_init(struct mmc_host *host)
>> +{
>> +       host->pre_defined_attr.show = mmc_cmd23_show;
>> +       host->pre_defined_attr.store = mmc_cmd23_store;
>> +       sysfs_attr_init(&host->pre_defined_attr.attr);
>> +       host->pre_defined_attr.attr.name = "pre_defined_op";
>> +       host->pre_defined_attr.attr.mode = S_IRUGO | S_IWUSR;
>> +       if (device_create_file(&host->class_dev, &host->pre_defined_attr))
>> +               pr_err("%s: Failed to create pre_defined_op sysfs entry\n",
>> +                               mmc_hostname(host));
>> +}
>> +
>>  /**
>>  *     mmc_alloc_host - initialise the per-host structure.
>>  *     @extra: sizeof private data structure
>> @@ -381,6 +416,10 @@ int mmc_add_host(struct mmc_host *host)
>>  #endif
>>        mmc_host_clk_sysfs_init(host);
>>
>> +       if (host->caps & MMC_CAP_CMD23)
>> +               host->pre_defined_op = 1;
>> +       mmc_host_cmd23_sysfs_init(host);
>> +
>>        mmc_start_host(host);
>>        register_pm_notifier(&host->pm_notify);
>>
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index 1a1ca71..b36d408 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -489,5 +489,6 @@ extern void mmc_unregister_driver(struct mmc_driver *);
>>
>>  extern void mmc_fixup_device(struct mmc_card *card,
>>                             const struct mmc_fixup *table);
>> +extern void mmc_change_operation_mode(struct mmc_card *card, int val);
>>
>>  #endif /* LINUX_MMC_CARD_H */
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index 20d7c82..59a30bf 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -259,6 +259,9 @@ struct mmc_host {
>>                                 MMC_CAP2_HS200_1_2V_SDR)
>>  #define MMC_CAP2_BROKEN_VOLTAGE        (1 << 7)        /* Use the broken voltage */
>>
>> +       struct device_attribute pre_defined_attr;
>> +       int                     pre_defined_op; /* CMD23 should be use or not */
>> +
>>        mmc_pm_flag_t           pm_caps;        /* supported pm features */
>>        unsigned int        power_notify_type;
>>  #define MMC_HOST_PW_NOTIFY_NONE                0
>> --
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