Re: [PATCH V2 03/27] mmc: mmci: convert dma_setup callback to return an int

From: Ulf Hansson <ulf.hansson@linaro.org>
To: Ludovic BARRE <ludovic.barre@st.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Gerald Baeza <gerald.baeza@st.com>,
	Loic Pallardy <loic.pallardy@st.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	DTML <devicetree@vger.kernel.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH V2 03/27] mmc: mmci: convert dma_setup callback to return an int
Date: Thu, 27 Sep 2018 01:49:39 +0200	[thread overview]
Message-ID: <CAPDyKFq2FmggcuRRYmeW-ChL-SiEboCTCu745kZHGeNLi_qQjg@mail.gmail.com> (raw)
In-Reply-To: <15c31e3b-646a-f5db-b45a-3e2f556d9fd5@st.com>

On 24 September 2018 at 18:12, Ludovic BARRE <ludovic.barre@st.com> wrote:
> hi Ulf
>
>
> On 09/24/2018 04:28 PM, Ulf Hansson wrote:
>>
>> On 21 September 2018 at 11:45, Ludovic Barre <ludovic.Barre@st.com> wrote:
>>>
>>> From: Ludovic Barre <ludovic.barre@st.com>
>>>
>>> This patch converts dma_setup callback to return an integer
>>> This patch is needed to prepare sdmmc variant with internal dma
>>>
>>> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
>>> ---
>>>   drivers/mmc/host/mmci.c          | 14 ++++++++++----
>>>   drivers/mmc/host/mmci.h          |  2 +-
>>>   drivers/mmc/host/mmci_qcom_dml.c |  6 ++++--
>>>   3 files changed, 15 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
>>> index cbd67bc..2f845f3 100644
>>> --- a/drivers/mmc/host/mmci.c
>>> +++ b/drivers/mmc/host/mmci.c
>>> @@ -415,7 +415,7 @@ static void mmci_init_sg(struct mmci_host *host,
>>> struct mmc_data *data)
>>>    * no custom DMA interfaces are supported.
>>>    */
>>>   #ifdef CONFIG_DMA_ENGINE
>>> -static void mmci_dma_setup(struct mmci_host *host)
>>> +static int mmci_dma_setup(struct mmci_host *host)
>>>   {
>>>          const char *rxname, *txname;
>>>
>>> @@ -466,7 +466,9 @@ static void mmci_dma_setup(struct mmci_host *host)
>>>          }
>>>
>>>          if (host->ops && host->ops->dma_setup)
>>> -               host->ops->dma_setup(host);
>>> +               return host->ops->dma_setup(host);
>>> +
>>
>>
>> Looks like you need to implement a error handling, instead of just
>> returning the error code.
>
>
> yes, today if a dma_setup is defined, we can't fallback to pio mode.
> A use_dma variable (defined in mmci_host) could be setted follow the return
> code of ops->dma_setup
>
> example:
>
> void mmci_dma_setup(struct mmci_host *host)
> {
>         int err;
>
>         if (!host->ops || !host->ops->dma_setup)
>                 return;
>
>         err = host->ops->dma_setup(host);
>         if (err)
>                 return;
>
>         host->use_dma = true;
>
>         /* initialize pre request cookie */
>         host->next_cookie = 1;
> }
>
> use_dma variable could be check by mmci_host_ops variant functions.
>
> are you agree with this proposal?
>

Yep, makes sense!

>
>>
>>> +       return 0;
>>>   }
>>>
>>>   /*
>>> @@ -741,8 +743,10 @@ static void mmci_post_request(struct mmc_host *mmc,
>>> struct mmc_request *mrq,
>>>   static void mmci_get_next_data(struct mmci_host *host, struct mmc_data
>>> *data)
>>>   {
>>>   }
>>> -static inline void mmci_dma_setup(struct mmci_host *host)
>>> +
>>> +static inline int mmci_dma_setup(struct mmci_host *host)
>>>   {
>>> +       return 0;
>>>   }
>>>
>>>   static inline void mmci_dma_release(struct mmci_host *host)
>>> @@ -1796,7 +1800,9 @@ static int mmci_probe(struct amba_device *dev,
>>>                   amba_rev(dev), (unsigned long long)dev->res.start,
>>>                   dev->irq[0], dev->irq[1]);
>>>
>>> -       mmci_dma_setup(host);
>>> +       ret = mmci_dma_setup(host);
>>> +       if (ret)
>>> +               goto clk_disable;
>>>
>>>          pm_runtime_set_autosuspend_delay(&dev->dev, 50);
>>>          pm_runtime_use_autosuspend(&dev->dev);
>>> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
>>> index 21aaf9a..06299ac 100644
>>> --- a/drivers/mmc/host/mmci.h
>>> +++ b/drivers/mmc/host/mmci.h
>>> @@ -273,7 +273,7 @@ struct variant_data {
>>>
>>>   /* mmci variant callbacks */
>>>   struct mmci_host_ops {
>>> -       void (*dma_setup)(struct mmci_host *host);
>>> +       int (*dma_setup)(struct mmci_host *host);
>>>   };
>>>
>>>   struct mmci_host_next {
>>> diff --git a/drivers/mmc/host/mmci_qcom_dml.c
>>> b/drivers/mmc/host/mmci_qcom_dml.c
>>> index be3fab5..1bb59cf 100644
>>> --- a/drivers/mmc/host/mmci_qcom_dml.c
>>> +++ b/drivers/mmc/host/mmci_qcom_dml.c
>>> @@ -119,7 +119,7 @@ static int of_get_dml_pipe_index(struct device_node
>>> *np, const char *name)
>>>   }
>>>
>>>   /* Initialize the dml hardware connected to SD Card controller */
>>> -static void qcom_dma_setup(struct mmci_host *host)
>>> +static int qcom_dma_setup(struct mmci_host *host)
>>>   {
>>>          u32 config;
>>>          void __iomem *base;
>>> @@ -131,7 +131,7 @@ static void qcom_dma_setup(struct mmci_host *host)
>>>
>>>          if (producer_id < 0 || consumer_id < 0) {
>>>                  host->variant->qcom_dml = false;
>>
>>
>> It seems like the existing code is an attempt to fallback to use pio
>> mode. However, I doubt it works as is.
>
>
> oops, I seen that like a variant identification issue, so if it's a
> fallback to pio mode it doesn't work.

Right. Let's see if we can get some input from Srinivas, else I will
run some test on my 410c board to see the behavior - very soon.

[...]

Kind regards
Uffe