mmc: mmci: Allow MMCI to request channels with information acquired from DT

> I think you can further simplify this, given that in the DT case we always
> allocate a zeroed mmci_platform_data for host->plat, so !plat cannot happen
> when we get here.

Okay, third time lucky. :)

On Thu, Apr 18, 2013 at 09:02:38AM +0100, Lee Jones wrote:
> @@ -321,19 +323,21 @@ static void mmci_dma_setup(struct mmci_host *host)
>  	 * attempt to use it bidirectionally, however if it is
>  	 * is specified but cannot be located, DMA will be disabled.
>  	 */
> -	if (plat->dma_rx_param) {
> -		host->dma_rx_channel = dma_request_channel(mask,
> -							   plat->dma_filter,
> -							   plat->dma_rx_param);
> +	if (plat->dma_rx_param || np) {
> +		host->dma_rx_channel = dma_request_slave_channel_compat(mask,
> +								plat->dma_filter,
> +								plat->dma_rx_param,
> +								&dev->dev, "rx");
>  		/* E.g if no DMA hardware is present */
>  		if (!host->dma_rx_channel)
>  			dev_err(mmc_dev(host->mmc), "no RX DMA channel\n");

I don't think this is right - I think Arnd has been leading you up the
garden path saying that this can be simplified.  Why?

If you look at what this code does, the DMA channels are optional.  If
they're not provided, then you don't get an error or a warning printk from
the code.  However, after your conversion, if you use DT and avoid giving
the DMA information (which you have to avoid on the majority of ARM
platforms) then "np" will be non-NULL, and
dma_request_slave_channel_compat() will return NULL, causing the error
and/or warning to be printed.

So, we really need to know whether the DMA channel information has been
provided in DT in the upper level "if" statement, and _not_ use
dma_request_slave_channel_compat().

On 18 April 2013 10:02, Lee Jones <lee.jones@linaro.org> wrote:
>> I think you can further simplify this, given that in the DT case we always
>> allocate a zeroed mmci_platform_data for host->plat, so !plat cannot happen
>> when we get here.
>
> Okay, third time lucky. :)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 372e921..3260ab4 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -298,14 +298,16 @@ 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 void mmci_dma_setup(struct amba_device *dev,
> +                          struct mmci_host *host)

Hi Lee,

You don't need to pass the amba_device, this can be fetched from the
mmci_host. Check how other functions converts the mmci host it in this
driver.

Kind regards
Ulf Hansson

>  {
> +       struct device_node *np = dev->dev.of_node;
>         struct mmci_platform_data *plat = host->plat;
>         const char *rxname, *txname;
>         dma_cap_mask_t mask;
>
> -       if (!plat || !plat->dma_filter) {
> -               dev_info(mmc_dev(host->mmc), "no DMA platform data\n");
> +       if (!(plat->dma_filter || np)) {
> +               dev_info(mmc_dev(host->mmc), "no DMA platform data or DT\n");
>                 return;
>         }
>
> @@ -321,19 +323,21 @@ static void mmci_dma_setup(struct mmci_host *host)
>          * attempt to use it bidirectionally, however if it is
>          * is specified but cannot be located, DMA will be disabled.
>          */
> -       if (plat->dma_rx_param) {
> -               host->dma_rx_channel = dma_request_channel(mask,
> -                                                          plat->dma_filter,
> -                                                          plat->dma_rx_param);
> +       if (plat->dma_rx_param || np) {
> +               host->dma_rx_channel = dma_request_slave_channel_compat(mask,
> +                                                               plat->dma_filter,
> +                                                               plat->dma_rx_param,
> +                                                               &dev->dev, "rx");
>                 /* E.g if no DMA hardware is present */
>                 if (!host->dma_rx_channel)
>                         dev_err(mmc_dev(host->mmc), "no RX DMA channel\n");
>         }
>
> -       if (plat->dma_tx_param) {
> -               host->dma_tx_channel = dma_request_channel(mask,
> -                                                          plat->dma_filter,
> -                                                          plat->dma_tx_param);
> +       if (plat->dma_tx_param || np) {
> +               host->dma_tx_channel = dma_request_slave_channel_compat(mask,
> +                                                               plat->dma_filter,
> +                                                               plat->dma_tx_param,
> +                                                               &dev->dev, "tx");
>                 if (!host->dma_tx_channel)
>                         dev_warn(mmc_dev(host->mmc), "no TX DMA channel\n");
>         } else {
> @@ -1538,7 +1542,7 @@ 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);
> +       mmci_dma_setup(dev, host);
>
>         pm_runtime_set_autosuspend_delay(&dev->dev, 50);
>         pm_runtime_use_autosuspend(&dev->dev);
>
> --
> Lee Jones
> Linaro ST-Ericsson Landing Team Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog
> --
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On Thu, Apr 18, 2013 at 11:25:44AM +0200, Arnd Bergmann wrote:
> +static void mmci_dma_setup(struct device *dev, struct mmci_host *host)
> +{
> +	const char *rxname, *txname;
> +
> +	host->dma_rx_channel = dma_request_slave_channel(dev, "rx");
> +	host->dma_tx_channel = dma_request_slave_channel(dev, "tx");
> +
> +	if (!host->dma_rx_channel && !host->dma_tx_channel) {
> +		if (host->plat && host->plat->dma_filter)
> +			mmci_dma_plat_setup(host);
> +		else
> +			dev_info(mmc_dev(host->mmc), "no DMA platform data\n");
> +			return;

You may like to fix the sillies in this patch... but yes, the above
would be better.