Re: [PATCH V4 02/25] mmc: mmci: create generic mmci_dma_setup

[Ludovic BARRE]

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