>> 2015-10-25 23:40 GMT+09:00 <ygardi@xxxxxxxxxxxxxx>:
>>>> 2015-09-02 19:13 GMT+09:00 Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>:
>>>>> Performing several writes to UFS host controller registers has
>>>>> no gurrantee of ordering, so we must make sure register writes
>>>>> to setup request list base address etc. are performed before the
>>>>> run/stop register is enabled.
>>>>> In addition, when setting up a task request, we must make sure
>>>>> the updating of descriptors takes places before ringing the
>>>>> doorbell, similarly to setting up a transfer request.
>>>>>
>>>>> Signed-off-by: Gilad Broner <gbroner@xxxxxxxxxxxxxx>
>>>>> Signed-off-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>
>>>>>
>>>>> ---
>>>>> drivers/scsi/ufs/ufshcd.c | 21 +++++++++++++++------
>>>>> 1 file changed, 15 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>>>> index fc2a52d..298511a 100644
>>>>> --- a/drivers/scsi/ufs/ufshcd.c
>>>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>>>> @@ -401,11 +401,9 @@ static inline int ufshcd_get_lists_status(u32
>>>>> reg)
>>>>> * 1 UTRLRDY
>>>>> * 2 UTMRLRDY
>>>>> * 3 UCRDY
>>>>> - * 4 HEI
>>>>> - * 5 DEI
>>>>> - * 6-7 reserved
>>>>> + * 4-7 reserved
>>>>> */
>>>>> - return (((reg) & (0xFF)) >> 1) ^ (0x07);
>>>>> + return ((reg & 0xFF) >> 1) ^ 0x07;
>>>>> }
>>>>>
>>>>> /**
>>>>> @@ -2726,7 +2724,7 @@ out:
>>>>> * To bring UFS host controller to operational state,
>>>>> * 1. Enable required interrupts
>>>>> * 2. Configure interrupt aggregation
>>>>> - * 3. Program UTRL and UTMRL base addres
>>>>> + * 3. Program UTRL and UTMRL base address
>>>>> * 4. Configure run-stop-registers
>>>>> *
>>>>> * Returns 0 on success, non-zero value on failure
>>>>> @@ -2756,8 +2754,13 @@ static int ufshcd_make_hba_operational(struct
>>>>> ufs_hba *hba)
>>>>> REG_UTP_TASK_REQ_LIST_BASE_H);
>>>>>
>>>>> /*
>>>>> + * Make sure base address and interrupt setup are updated
>>>>> before
>>>>> + * enabling the run/stop registers below.
>>>>> + */
>>>>> + wmb();
>>>>> +
>>>>> + /*
>>>>> * UCRDY, UTMRLDY and UTRLRDY bits must be 1
>>>>> - * DEI, HEI bits must be 0
>>>>> */
>>>>> reg = ufshcd_readl(hba, REG_CONTROLLER_STATUS);
>>>>> if (!(ufshcd_get_lists_status(reg))) {
>>>>> @@ -3920,7 +3923,13 @@ static int ufshcd_issue_tm_cmd(struct ufs_hba
>>>>> *hba, int lun_id, int task_id,
>>>>>
>>>>> /* send command to the controller */
>>>>> __set_bit(free_slot, &hba->outstanding_tasks);
>>>>> +
>>>>> + /* Make sure descriptors are ready before ringing the task
>>>>> doorbell */
>>>>> + wmb();
>>>>> +
>>>>> ufshcd_writel(hba, 1 << free_slot,
>>>>> REG_UTP_TASK_REQ_DOOR_BELL);
>>>>> + /* Make sure that doorbell is committed immediately */
>>>>> + wmb();
>>>>
>>>> Is this wmb() after ringing tm doorbell is needed?
>>>
>>> Well, Mita, in the case of DB register (Request DB and TASK DB), every
>>> write operation to the DB should be barrier, as if not, out of order
>>> writing to this register might cause inconsistency in its value, and
>>> thus,
>>> un-handled requests/tasks.
>>
>> I couldn't fully understand why out of order writing to TASK DB
>> register causes inconsistency.
>> In the TASK request completion (ufshcd_tmc_handler), TASK DB register
>> is read before handling finished requests, so it ensures that all
>> write operations for TASK DB have been performed.
>>
>
> thanks, Mita
> your explanation makes sense.
> It will be fixed in v4.
>
sorry, it will fixed in v5.
Yaniv
>
>>>>
>>>>>
>>>>> spin_unlock_irqrestore(host->host_lock, flags);
>>>>>
>>>>> --
>>>>> 1.8.5.2
>>>>>
>>>>> --
>>>>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>>>>> member of Code Aurora Forum, hosted by The Linux Foundation
>>>>> --
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>>>>
>>>
>>>
>>
>
>
>
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