lkml.org 
[lkml]   [2020]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v4 1/3] mmc: host: Introduce the request_atomic() for the host
From
Date
On 7/04/20 10:21 am, Baolin Wang wrote:
> On Tue, Apr 7, 2020 at 2:38 PM Adrian Hunter <adrian.hunter@intel.com> wrote:
>>
>> On 3/04/20 10:05 am, Baolin Wang wrote:
>>> The SD host controller can process one request in the atomic context if
>>> the card is nonremovable, which means we can submit next request in the
>>> irq hard handler when using the MMC host software queue to reduce the
>>> latency. Thus this patch adds a new API request_atomic() for the host
>>> controller, as well as adding support for host software queue to submit
>>> a request by the new request_atomic() API.
>>>
>>> Moreover there is an unusual case that the card is busy when trying to
>>> send a command, and we can not polling the card status in interrupt
>>> context by using request_atomic() to dispatch requests. Thus we should
>>> queue a work to try again in the non-atomic context in case the host
>>> releases the busy signal later.
>>>
>>> Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
>>> Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
>>
>>
>> One minor point below, otherwise:
>>
>> Acked-by: Adrian Hunter <adrian.hunter@intel.com>
>>
>>> ---
>>> drivers/mmc/host/mmc_hsq.c | 29 ++++++++++++++++++++++++++++-
>>> drivers/mmc/host/mmc_hsq.h | 1 +
>>> include/linux/mmc/host.h | 3 +++
>>> 3 files changed, 32 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/host/mmc_hsq.c b/drivers/mmc/host/mmc_hsq.c
>>> index b90b2c9..a57f802 100644
>>> --- a/drivers/mmc/host/mmc_hsq.c
>>> +++ b/drivers/mmc/host/mmc_hsq.c
>>> @@ -16,11 +16,20 @@
>>> #define HSQ_NUM_SLOTS 64
>>> #define HSQ_INVALID_TAG HSQ_NUM_SLOTS
>>>
>>> +static void mmc_hsq_retry_handler(struct work_struct *work)
>>> +{
>>> + struct mmc_hsq *hsq = container_of(work, struct mmc_hsq, retry_work);
>>> + struct mmc_host *mmc = hsq->mmc;
>>> +
>>> + mmc->ops->request(mmc, hsq->mrq);
>>> +}
>>> +
>>> static void mmc_hsq_pump_requests(struct mmc_hsq *hsq)
>>> {
>>> struct mmc_host *mmc = hsq->mmc;
>>> struct hsq_slot *slot;
>>> unsigned long flags;
>>> + int ret = 0;
>>>
>>> spin_lock_irqsave(&hsq->lock, flags);
>>>
>>> @@ -42,7 +51,24 @@ static void mmc_hsq_pump_requests(struct mmc_hsq *hsq)
>>>
>>> spin_unlock_irqrestore(&hsq->lock, flags);
>>>
>>> - mmc->ops->request(mmc, hsq->mrq);
>>> + if (mmc->ops->request_atomic)
>>> + ret = mmc->ops->request_atomic(mmc, hsq->mrq);
>>> + else
>>> + mmc->ops->request(mmc, hsq->mrq);
>>> +
>>> + /*
>>> + * If returning BUSY from request_atomic(), which means the card
>>> + * may be busy now, and we should change to non-atomic context to
>>> + * try again for this unusual case, to avoid time-consuming operations
>>> + * in the atomic context.
>>> + *
>>> + * Note: we just give a warning for other error cases, since the host
>>> + * driver will handle them.
>>> + */
>>> + if (ret == -EBUSY)
>>> + schedule_work(&hsq->retry_work);
>>> + else
>>> + WARN_ON_ONCE(ret && ret != -EBUSY);
>>
>> 'ret != -EBUSY' is redundant because it is always true in the 'else' clause.
>
> Ah, Yes, thanks for pointing this out and I will fix it ine next version.
>
> By the way, could you help to review patch 2 and 3 in this patch set? Thanks.
>

I'd like to handle the inhibit wait differently. I will make some patches
for that and send them out.

\
 
 \ /
  Last update: 2020-04-07 12:15    [W:0.074 / U:13.476 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site