linux-kernel - Re: [PATCH v3 4/7] of: configure the platform device dma parameters

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Date:	Thu, 1 May 2014 19:49:05 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Santosh Shilimkar <santosh.shilimkar@...com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Grygorii Strashko <grygorii.strashko@...com>
Subject: Re: [PATCH v3 4/7] of: configure the platform device dma parameters

On Thu, Apr 24, 2014 at 10:30 AM, Santosh Shilimkar
<santosh.shilimkar@...com> wrote:
> Retrieve DMA configuration from DT and setup platform device's DMA
> parameters. The DMA configuration in DT has to be specified using
> "dma-ranges" and "dma-coherent" properties if supported.
>
> We setup dma_pfn_offset using "dma-ranges" and dma_coherent_ops
> using "dma-coherent" device tree properties.
>
> The set_arch_dma_coherent_ops macro has to be defined by arch if
> it supports coherent dma_ops. Otherwise, set_arch_dma_coherent_ops() is
> declared as nop.
>

[...]

> +       /*
> +        * if dma-ranges property doesn't exist - just return else
> +        * setup the dma offset
> +        */
> +       ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
> +       if ((ret == -ENODEV) || (ret < 0)) {

The 1st condition is redundant.

> +               dev_dbg(dev, "no dma range information to setup\n");
> +               return;
> +       }
> +
> +       /* DMA ranges found. Calculate and set dma_pfn_offset */
> +       dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
> +       dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
> +}
> +
> +/**
>   * of_platform_device_create_pdata - Alloc, initialize and register an of_device
>   * @np: pointer to node to create device for
>   * @bus_id: name to assign device
> @@ -214,9 +258,7 @@ static struct platform_device *of_platform_device_create_pdata(
>  #if defined(CONFIG_MICROBLAZE)
>         dev->archdata.dma_mask = 0xffffffffUL;
>  #endif

This is also dma related setup. Please move *all* dma setup into the function.

> -       dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> -       if (!dev->dev.dma_mask)
> -               dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
> +       of_dma_configure(&dev->dev);
>         dev->dev.bus = &platform_bus_type;
>         dev->dev.platform_data = platform_data;
>
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index fd4aee2..c7d9b1b 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -123,6 +123,13 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
>
>  extern u64 dma_get_required_mask(struct device *dev);
>
> +#ifndef set_arch_dma_coherent_ops
> +static inline int set_arch_dma_coherent_ops(struct device *dev)
> +{
> +       return 0;
> +}
> +#endif
> +
>  static inline unsigned int dma_get_max_seg_size(struct device *dev)
>  {
>         return dev->dma_parms ? dev->dma_parms->max_segment_size : 65536;
> --
> 1.7.9.5
>
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