linux-kernel - Re: [PATCH V5 02/24] mmc: mmci: create common mmci_dma

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Date:   Fri, 5 Oct 2018 15:47:12 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Ludovic Barre <ludovic.Barre@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH V5 02/24] mmc: mmci: create common mmci_dma_setup/release

On 5 October 2018 at 15:22, Ludovic Barre <ludovic.Barre@...com> wrote:
> From: Ludovic Barre <ludovic.barre@...com>
>
> This patch creates a common mmci_dma_setup/release which calls
> dma_setup/release callbacks of mmci_host_ops and manages
> common features like use_dma... If there is a fallbacks to
> pio mode, dma functions must check use_dma.
>
> error management:
> -mmci_dmae_setup fail if Tx and Rx dma channels are not defined
> -qcom_dma_setup fail if one of both dma channels is not defined,
>  Qcom has no specific resource to release, just mmci dmae resource.

Makes perfect sense!

[...]

> +void mmci_dma_setup(struct mmci_host *host)
> +{
> +       if (!host->ops || !host->ops->dma_setup)
> +               return;
> +
> +       if (host->ops->dma_setup(host)) {
> +               mmci_dma_release(host);

Please remove this and let the variants clean up themselves. That
makes it more straight forward.

> +               return;
> +       }
> +
> +       host->use_dma = true;
> +}
> +

[...]

> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index 01e6c6b..9b0a960 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -273,7 +273,8 @@ struct variant_data {
>
>  /* mmci variant callbacks */
>  struct mmci_host_ops {
> -       void (*dma_setup)(struct mmci_host *host);
> +       int (*dma_setup)(struct mmci_host *host);
> +       void (*dma_release)(struct mmci_host *host);
>  };
>
>  struct mmci_host_next {
> @@ -323,6 +324,7 @@ 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 +338,14 @@ struct mmci_host {
>  #endif
>  };
>
> +#ifdef CONFIG_DMA_ENGINE
> +void mmci_variant_init(struct mmci_host *host);
> +#else
> +static inline void mmci_variant_init(struct mmci_host *host)
> +{
> +}
> +#endif

This can be kept in mmci.c instead.

> +
> +int mmci_dmae_setup(struct mmci_host *host);
> +void mmci_dmae_release(struct mmci_host *host);
> +
> diff --git a/drivers/mmc/host/mmci_qcom_dml.c b/drivers/mmc/host/mmci_qcom_dml.c
> index be3fab5..aa070a9 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;

This relies on error handling to be done by mmci_dma_setup(), which as
stated, feels a bit wrong.

I would rather just call mmci_dmae_realease() here, before returning -EINVAL.

[...]

Otherwise, this looks good to me now.

Kind regards
Uffe