linux-kernel - Re: [PATCH v4 2/3] mmc: host: sdhci: Add request_done ops for struct sdhci

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Date:   Mon, 28 Oct 2019 11:10:13 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>, asutoshd@...eaurora.org,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        baolin.wang7@...il.com, linux-mmc <linux-mmc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/3] mmc: host: sdhci: Add request_done ops for struct
 sdhci_ops

On 28/10/19 10:38 AM, Baolin Wang wrote:
> On Mon, 28 Oct 2019 at 16:27, Baolin Wang <baolin.wang@...aro.org> wrote:
>>
>> Hi Adrian,
>>
>> On Mon, 28 Oct 2019 at 16:20, Adrian Hunter <adrian.hunter@...el.com> wrote:
>>>
>>> On 22/10/19 8:58 AM, Baolin Wang wrote:
>>>> Add request_done ops for struct sdhci_ops as a preparation in case some
>>>> host controllers have different method to complete one request, such as
>>>> supporting request completion of MMC software queue.
>>>>
>>>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>>>> ---
>>>>  drivers/mmc/host/sdhci.c |   12 ++++++++++--
>>>>  drivers/mmc/host/sdhci.h |    2 ++
>>>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>> index b056400..850241f 100644
>>>> --- a/drivers/mmc/host/sdhci.c
>>>> +++ b/drivers/mmc/host/sdhci.c
>>>> @@ -2729,7 +2729,10 @@ static bool sdhci_request_done(struct sdhci_host *host)
>>>>
>>>>       spin_unlock_irqrestore(&host->lock, flags);
>>>>
>>>> -     mmc_request_done(host->mmc, mrq);
>>>> +     if (host->ops->request_done)
>>>> +             host->ops->request_done(host, mrq);
>>>
>>> For hsq, couldn't this result in sdhci_request() being called interrupt
>>> context here.
>>
>> Right, now it did not support.
>>
>>>
>>> To prevent that you would need to add a condition to sdhci_defer_done() so
>>> it always defers when using hsq.
>>
>> Yes, but now the condition can be matched in sdhci_defer_done()  when
>> using hsq. So no need to worry that the sdhci_request() will be called
>> in interrupt
>> context in this patch set. Thanks.
>>
> 
> Wait, sorry, I realized some drivers may not select the
> SDHCI_REQ_USE_DMA flag in sdhci_defer_done()  when using hsq. OK, So
> how about below changes?
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 850241f..6c7a396 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3035,7 +3035,7 @@ static inline bool sdhci_defer_done(struct
> sdhci_host *host,
>  {
>         struct mmc_data *data = mrq->data;
> 
> -       return host->pending_reset ||
> +       return IS_ENABLED(CONFIG_MMC_HSQ) || host->pending_reset ||

Just because it is configured does not mean it is used.  How about adding a
variable host->always_defer_done and set it in sdhci_sprd_probe().

>                ((host->flags & SDHCI_REQ_USE_DMA) && data &&
>                 data->host_cookie == COOKIE_MAPPED);
>  }
>