linux-kernel - Re: [RFC/PATCH 3/9] of: dma: Move range size workaround to of_dma_get

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Message-ID: <20150527175922.GE4232@arm.com>
Date:	Wed, 27 May 2015 18:59:23 +0100
From:	Will Deacon <will.deacon@....com>
To:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	Laura Abbott <lauraa@...eaurora.org>,
	Arnd Bergmann <arnd@...db.de>,
	Mitchel Humpherys <mitchelh@...eaurora.org>,
	Joreg Roedel <joro@...tes.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Robin Murphy <Robin.Murphy@....com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [RFC/PATCH 3/9] of: dma: Move range size workaround to
 of_dma_get_range()

On Fri, May 15, 2015 at 12:00:04AM +0100, Laurent Pinchart wrote:
> Invalid dma-ranges values should be worked around when retrieving the
> DMA range in of_dma_get_range(), not by all callers of the function.
> This isn't much of a problem now that we have a single caller, but that
> situation will change when moving DMA configuration to device probe
> time.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> ---
>  drivers/of/address.c | 20 ++++++++++++++++++--
>  drivers/of/device.c  | 15 ---------------
>  2 files changed, 18 insertions(+), 17 deletions(-)

Looks good to me:

  Acked-by: Will Deacon <will.deacon@....com>

Will

> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 78a7dcbec7d8..75eebd19ebfa 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -924,8 +924,8 @@ EXPORT_SYMBOL(of_io_request_and_map);
>   *	CPU addr (phys_addr_t)	: pna cells
>   *	size			: nsize cells
>   *
> - * It returns -ENODEV if "dma-ranges" property was not found
> - * for this device in DT.
> + * Return 0 on success, -ENODEV if the "dma-ranges" property was not found for
> + * this device in DT, or -EINVAL if the CPU address or size is invalid.
>   */
>  int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *size)
>  {
> @@ -986,6 +986,22 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
>  	*dma_addr = dmaaddr;
>  
>  	*size = of_read_number(ranges + naddr + pna, nsize);
> +	/*
> +	 * DT nodes sometimes incorrectly set the size as a mask. Work around
> +	 * those incorrect DT by computing the size as mask + 1.
> +	 */
> +	if (*size & 1) {
> +		pr_warn("%s: size 0x%llx for dma-range in node(%s) set as mask\n",
> +			__func__, *size, np->full_name);
> +		*size = *size + 1;
> +	}
> +
> +	if (!*size) {
> +		pr_err("%s: invalid size zero for dma-range in node(%s)\n",
> +		       __func__, np->full_name);
> +		ret = -EINVAL;
> +		goto out;
> +	}
>  
>  	pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
>  		 *dma_addr, *paddr, *size);
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 20c1332a0018..530aa1ed3e1b 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -109,21 +109,6 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>  		size = dev->coherent_dma_mask + 1;
>  	} else {
>  		offset = PFN_DOWN(paddr - dma_addr);
> -
> -		/*
> -		 * Add a work around to treat the size as mask + 1 in case
> -		 * it is defined in DT as a mask.
> -		 */
> -		if (size & 1) {
> -			dev_warn(dev, "Invalid size 0x%llx for dma-range\n",
> -				 size);
> -			size = size + 1;
> -		}
> -
> -		if (!size) {
> -			dev_err(dev, "Adjusted size 0x%llx invalid\n", size);
> -			return;
> -		}
>  		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
>  	}
>  
> -- 
> 2.3.6
> 
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