Re: [PATCH] blackfin: include: asm: pgtable: Define dummy pgprot_writecombine

[Richard Weinberger <richard@nod.at>]

Am 05.04.2015 um 00:02 schrieb Chen Gang:
> On 4/4/15 06:50, Richard Weinberger wrote:
>> On Fri, Apr 3, 2015 at 10:36 PM, Chen Gang <xili_gchen_5257@hotmail.com> wrote:
>>> It is copied from asm-generic, the related error with allmodconfig:
>>>
>>>     CC [M]  sound/core/pcm_native.o
>>>   sound/core/pcm_native.c: In function 'snd_pcm_lib_default_mmap':
>>>   sound/core/pcm_native.c:3387:24: error: implicit declaration of function 'pgprot_writecombine' [-Werror=implicit-function-declaration]
>>>      area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
>>>                           ^
>>>   sound/core/pcm_native.c:3387:22: error: incompatible types when assigning to type 'pgprot_t {aka struct <anonymous>}' from type 'int'
>>>      area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
>>>                         ^
>>>
>>> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
>>> ---
>>>  arch/blackfin/include/asm/pgtable.h | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/blackfin/include/asm/pgtable.h b/arch/blackfin/include/asm/pgtable.h
>>> index b88a155..3e730d9 100644
>>> --- a/arch/blackfin/include/asm/pgtable.h
>>> +++ b/arch/blackfin/include/asm/pgtable.h
>>> @@ -36,6 +36,7 @@ typedef pte_t *pte_addr_t;
>>>  #define PAGE_READONLY          __pgprot(0)     /* these mean nothing to NO_MM */
>>>  #define PAGE_KERNEL            __pgprot(0)     /* these mean nothing to NO_MM */
>>>  #define pgprot_noncached(prot) (prot)
>>> +#define pgprot_writecombine    pgprot_noncached
>>
>> This looks fishy as blackfin's pgtable.h already includes asm-generic/pgtable.h.
>> So, copy&pasting pgprot_writecombine shouldn't be needed.
>>
> 
> pgprot_writecombine in asm-generic/pgtable.h needs MMU, but allmodconfig
> for blackfin is NOMMU.
> 
> So, I still suggest to add dummy one in blackfin (although for me, asm-
> generic/pgtable.h may need improvement -- welcome other members for it).

Sounds still fishy as you "introduced" allmodconfig...

Thanks,
//richard