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Message-ID: <CAL_JsqJJ4Cbh5poMa-KRwy+bp_t3VtRd7bCpcWey+DZ74eYHJQ@mail.gmail.com>
Date: Mon, 21 Apr 2014 09:58:17 -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 v2 4/7] of: configure the platform device dma parameters
On Sat, Apr 19, 2014 at 9:32 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.
>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Olof Johansson <olof@...om.net>
> Cc: Grant Likely <grant.likely@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
> ---
> drivers/of/platform.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/dma-mapping.h | 7 +++++++
> 2 files changed, 50 insertions(+)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 573db15..7e4a43b 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -187,6 +187,47 @@ struct platform_device *of_device_alloc(struct device_node *np,
> EXPORT_SYMBOL(of_device_alloc);
>
> /**
> + * of_dma_configure - Setup DMA configuration
> + * @dev: Device to apply DMA configuration
> + *
> + * Try to get devices's DMA configuration from DT and update it
> + * accordingly.
> + *
> + * In case if platform code need to use own special DMA configuration,it
> + * can use Platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE event
> + * to fix up DMA configuration.
> + */
> +static void of_dma_configure(struct device *dev)
> +{
> + dma_addr_t dma_addr;
> + phys_addr_t paddr, size;
A problem with using dma_addr_t and phys_addr_t is that they normally
depend on CONFIG_LPAE, but the address cell sizes are independent of
that. That is why all the memory related functions stick with u64. I
think you would have issues here if you have a platform with sizes of
4GB or more. You need to properly cap the sizes and addresses.
> + int ret;
> +
> + /*
> + * if dma-coherent property exist, call arch hook to setup
> + * dma coherent operations.
> + */
> + if (of_dma_is_coherent(dev->of_node)) {
> + set_arch_dma_coherent_ops(dev);
> + dev_dbg(dev, "device is dma coherent\n");
> + }
> +
> + /*
> + * 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 < 0) {
Perhaps an error is not the right return for the default case. The
default should probably be dma_addr and paddr equal to 0 and size 4GB.
> + dev_dbg(dev, "no dma range information to setup\n");
> + return;
> + } else {
You don't need the else here.
> + /* 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
> @@ -217,6 +258,8 @@ static struct platform_device *of_platform_device_create_pdata(
> dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> if (!dev->dev.dma_mask)
> dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
You should move all DMA related setup into of_dma_configure.
> +
> + 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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