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Subject: Re: [PATCH V4 02/25] mmc: mmci: create generic mmci_dma_setup
To:     Ulf Hansson <ulf.hansson@linaro.org>
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>
References: <1538482167-13819-1-git-send-email-ludovic.Barre@st.com>
 <1538482167-13819-3-git-send-email-ludovic.Barre@st.com>
 <CAPDyKFpZKdZ5Oh29_EpgDqpwppa63Uci-FeLHF2KZBxVcO4COQ@mail.gmail.com>
From:   Ludovic BARRE <ludovic.barre@st.com>
Message-ID: <a4257361-b6ad-3ccc-1ade-303065744bad@st.com>
Date:   Wed, 3 Oct 2018 13:44:01 +0200
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hi Ulf

On 10/03/2018 11:22 AM, Ulf Hansson wrote:
> + Srinivas

for next series, I will add Srinivas

> 
> [...]
> 
>>   #ifdef CONFIG_DMA_ENGINE
>> -static void mmci_dma_setup(struct mmci_host *host)
>> +static inline void mmci_dma_release(struct mmci_host *host);
>> +
>> +int mmci_dmae_setup(struct mmci_host *host)
>>   {
>>          const char *rxname, *txname;
>>
>> @@ -464,8 +485,12 @@ static void mmci_dma_setup(struct mmci_host *host)
>>                          host->mmc->max_seg_size = max_seg_size;
>>          }
>>
>> -       if (host->ops && host->ops->dma_setup)
>> -               host->ops->dma_setup(host);
>> +       if (!host->dma_tx_channel || !host->dma_rx_channel) {
>> +               mmci_dma_release(host);
> 
> This doesn't look right to me. The existing code allows a tx channel
> to be used, even if an rx channel could not be setup. It seems
> reasonable to still allow that.

ok, I could replace by
if (!host->dma_tx_channel && !host->dma_rx_channel)

> 
>> +               return -EINVAL;
>> +       }
>> +
>> +       return 0;
>>   }
>>
>>   /*
>> @@ -496,7 +521,7 @@ static void mmci_dma_unmap(struct mmci_host *host, struct mmc_data *data)
>>
>>   static void mmci_dma_data_error(struct mmci_host *host)
>>   {
>> -       if (!dma_inprogress(host))
>> +       if (!host->use_dma || !dma_inprogress(host))
> 
> Adding the check for use_dma here seems like an unnecessary check,
> unless there is a reason for it due to following changes on top. In
> such case, please make it a part of the patch(es) where it's actually
> needed.

In Fact, these checks are add to ensure the pio fallback, if only this 
patch it's taken. In the next commit of serie, these checks are moved to 
common functions mmci_dma_XX function.

> 
>>                  return;
>>
>>          dev_err(mmc_dev(host->mmc), "error during DMA transfer!\n");
>> @@ -514,7 +539,7 @@ static void mmci_dma_finalize(struct mmci_host *host, struct mmc_data *data)
>>          u32 status;
>>          int i;
>>
>> -       if (!dma_inprogress(host))
>> +       if (!host->use_dma || !dma_inprogress(host))
> 
> Ditto.
> 
>>                  return;
>>
>>          /* Wait up to 1ms for the DMA to complete */
>> @@ -546,6 +571,7 @@ static void mmci_dma_finalize(struct mmci_host *host, struct mmc_data *data)
>>          if (status & MCI_RXDATAAVLBLMASK) {
>>                  dev_err(mmc_dev(host->mmc), "buggy DMA detected. Taking evasive action.\n");
>>                  mmci_dma_release(host);
>> +               host->use_dma = false;
>>          }
>>
>>          host->dma_in_progress = false;
>> @@ -640,6 +666,9 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
>>          int ret;
>>          struct mmc_data *data = host->data;
>>
>> +       if (!host->use_dma)
>> +               return -EINVAL;
>> +
>>          ret = mmci_dma_prep_data(host, host->data);
>>          if (ret)
>>                  return ret;
>> @@ -674,6 +703,9 @@ static void mmci_get_next_data(struct mmci_host *host, struct mmc_data *data)
>>   {
>>          struct mmci_host_next *next = &host->next_data;
>>
>> +       if (!host->use_dma)
>> +               return;
>> +
>>          WARN_ON(data->host_cookie && data->host_cookie != next->cookie);
>>          WARN_ON(!data->host_cookie && (next->dma_desc || next->dma_chan));
>>
>> @@ -689,7 +721,7 @@ static void mmci_pre_request(struct mmc_host *mmc, struct mmc_request *mrq)
>>          struct mmc_data *data = mrq->data;
>>          struct mmci_host_next *nd = &host->next_data;
>>
>> -       if (!data)
>> +       if (!host->use_dma || !data)
>>                  return;
>>
>>          BUG_ON(data->host_cookie);
>> @@ -707,7 +739,7 @@ static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq,
>>          struct mmci_host *host = mmc_priv(mmc);
>>          struct mmc_data *data = mrq->data;
>>
>> -       if (!data || !data->host_cookie)
>> +       if (!host->use_dma || !data || !data->host_cookie)
> 
> Ditto.
> 
>>                  return;
>>
>>          mmci_dma_unmap(host, data);
>> @@ -735,14 +767,14 @@ static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq,
>>          }
>>   }
>>
>> +static struct mmci_host_ops mmci_variant_ops = {
>> +       .dma_setup = mmci_dmae_setup,
>> +};
>>   #else
>>   /* Blank functions if the DMA engine is not available */
>>   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 void mmci_dma_release(struct mmci_host *host)
>>   {
>> @@ -765,8 +797,14 @@ static inline int mmci_dma_start_data(struct mmci_host *host, unsigned int datac
>>   #define mmci_pre_request NULL
>>   #define mmci_post_request NULL
>>
>> +static struct mmci_host_ops mmci_variant_ops = {};
> 
> This seems a bit unnecessary. See more about why, below.
> 
>>   #endif
>>
>> +void mmci_variant_init(struct mmci_host *host)
> 
> Looks like you should make mmci_variant_init() internal to mmci.c,
> thus covert it to static.
> 
> Moreover, I suggest you define a "static inline void
> mmci_variant_init()", when CONFIG_DMA_ENGINE is unset. In that way you
> don't need to assign host->ops at all for this case.

OK, no problem

> 
>> +{
>> +       host->ops = &mmci_variant_ops;
>> +}
>> +
>>   static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
>>   {
>>          struct variant_data *variant = host->variant;
>> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
>> index 01e6c6b..f7fe80f 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 {
>> @@ -323,6 +323,7 @@ struct mmci_host {
>>          unsigned int            size;
>>          int (*get_rx_fifocnt)(struct mmci_host *h, u32 status, int remain);
>>
>> +       u8                      use_dma:1;
>>   #ifdef CONFIG_DMA_ENGINE
>>          /* DMA stuff */
>>          struct dma_chan         *dma_current;
>> @@ -336,3 +337,7 @@ struct mmci_host {
>>   #endif
>>   };
>>
>> +void mmci_variant_init(struct mmci_host *host);
>> +
>> +int mmci_dmae_setup(struct mmci_host *host);
>> +
>> diff --git a/drivers/mmc/host/mmci_qcom_dml.c b/drivers/mmc/host/mmci_qcom_dml.c
>> index be3fab5..c8d7592 100644
>> --- a/drivers/mmc/host/mmci_qcom_dml.c
>> +++ b/drivers/mmc/host/mmci_qcom_dml.c
>> @@ -119,19 +119,22 @@ 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;
>>          int consumer_id, producer_id;
>>          struct device_node *np = host->mmc->parent->of_node;
>>
>> +       if (mmci_dmae_setup(host))
>> +               return -EINVAL;
>> +
>>          consumer_id = of_get_dml_pipe_index(np, "tx");
>>          producer_id = of_get_dml_pipe_index(np, "rx");
>>
>>          if (producer_id < 0 || consumer_id < 0) {
>>                  host->variant->qcom_dml = false;
>> -               return;
>> +               return -EINVAL;
> 
> Seems like you need to call a corresponding dma release function here,
> before returning the error code.
> 
> Probably an "mmci_dmae_release()" needs to be implemented as a part of
> this change - and then also called from here. This is according to
> Srinivas recommendations, which means falling back to pio. As a matter
> of fact this also needs to be clearly stated in the changelog, as you
> are really also improving the behavior for the Qcom variant.

it's in relation with the comment on
+       if (!host->dma_tx_channel || !host->dma_rx_channel) {

So yes.
At first sight Qcom need to have a tx and rx channel,
I will add mmci_dmae_release before returning error code.

> 
> Unfortunate, I am not able to test this as I don't have the HW (which
> I thought I had). Perhaps Srinivas can help, once we have something
> ready for him to test.
> 
>>          }
>>
>>          base = host->base + DML_OFFSET;
>> @@ -175,6 +178,8 @@ static void qcom_dma_setup(struct mmci_host *host)
>>
>>          /* Make sure dml initialization is finished */
>>          mb();
>> +
>> +       return 0;
>>   }
>>
>>   static struct mmci_host_ops qcom_variant_ops = {
>> --
>> 2.7.4
>>
> 
> Kind regards
> Uffe
>