[Top] [All Lists]

Re: [PATCH RFT RESEND linux-next] mips: dma-mapping: support debug_dma_m

Subject: Re: [PATCH RFT RESEND linux-next] mips: dma-mapping: support debug_dma_mapping_error
From: David Daney <>
Date: Fri, 26 Oct 2012 13:07:02 -0700
Cc:,,,,,, LKML <>,
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=+rG7qIv0WXUwOIsvxebQ9BHxdXXvQ3DzGAmARhbLsHI=; b=LHSQ60zDqShZYtBmO/+dnmT+PzSpWTFOEErgK7F8knk1rgdw/8Bvhj8C1cWUJ9DVPK QC8kh32NFLdMLlzFXJEoNWQOmPKBocgIJsGm+QeMkbvUIQVEyTwU+tI3bj6sE3TpWtq+ KieaY8ejz0q2QBe24DGtqe+EHylZOI+VnurInnuQ+5tKELljmFd4x5vC3FO7TRFZT9h1 w7IBRpeqhcTEZ2T8qcTfIAmz0gP7NCZ4lAfu85wFpdc7qoZHN35PiU1Un+gZjPFeo4OH XkTLf8FjipAnVYp4vCfyrTUAQAdFnF1oyDzk2wQqqZiAmobOUpwhM6uiBQHiClTTtpXR FqBQ==
In-reply-to: <1351271198.4013.35.camel@lorien2>
List-archive: <>
List-help: <>
List-id: linux-mips <>
List-owner: <>
List-post: <>
List-software: Ecartis version 1.0.0
List-subscribe: <>
List-unsubscribe: <>
References: <1351208193.6851.17.camel@lorien2> <1351267298.4013.12.camel@lorien2> <> <1351271198.4013.35.camel@lorien2>
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121016 Thunderbird/16.0.1
On 10/26/2012 10:06 AM, Shuah Khan wrote:
On Fri, 2012-10-26 at 09:45 -0700, David Daney wrote:
On 10/26/2012 09:01 AM, Shuah Khan wrote:
Add support for debug_dma_mapping_error() call to avoid warning from
debug_dma_unmap() interface when it checks for mapping error checked
status. Without this patch, device driver failed to check map error
warning is generated.

Signed-off-by: Shuah Khan <>
   arch/mips/include/asm/dma-mapping.h |    2 ++
   1 file changed, 2 insertions(+)

diff --git a/arch/mips/include/asm/dma-mapping.h 
index be39a12..006b43e 100644
--- a/arch/mips/include/asm/dma-mapping.h
+++ b/arch/mips/include/asm/dma-mapping.h
@@ -40,6 +40,8 @@ static inline int dma_supported(struct device *dev, u64 mask)
   static inline int dma_mapping_error(struct device *dev, u64 mask)
        struct dma_map_ops *ops = get_dma_ops(dev);
+       debug_dma_mapping_error(dev, mask);
        return ops->mapping_error(dev, mask);

Although this is a start, I don't think it is sufficient.

As far as I can tell, there are many missing calls to debug_dma_*() in
the various MIPS commone and sub-architecture DMA code.

Really you (or someone) needs to look at *all* the functions in
arch/mips/asm/dma-mapping.h, and arch/mips/mm/dma-default.c and find
places missing a debug_dma_*().

Is it correct to assume that this patch is not needed on MIPS until
debug_dma interfaces get added to MIPS common and sub-architecture DMA

No, you have a false predicate here.

debug_dma_* *is* already mostly added. The problem is that it is incomplete. That is the nature of the problem. Your patch makes it slightly better, but doesn't fully fix the problems.

When I didn't see dma_map_page() in arch/mips/include/asm/dma-mapping.h
defined, and just an extern, I incorrectly assumed, it is getting picked
up from <asm-generic/dma-mapping-common.h>, hence the need for this
patch in the first place.

-- Shuah

<Prev in Thread] Current Thread [Next in Thread>