[U-Boot] [PATCH 2/3] bouncebuf: Add DMA validation check to addr_aligned().

[Christoph Müllner]

On 07.05.19 17:04, Marek Vasut wrote:
> On 5/7/19 4:01 PM, Christoph Müllner wrote:
>>
>>
>> On 07.05.19 15:53, Marek Vasut wrote:
>>> On 5/7/19 3:52 PM, Christoph Müllner wrote:
>>>>
>>>>
>>>> On 5/7/19 3:48 PM, Christoph Müllner wrote:
>>>>>
>>>>>
>>>>> On 07.05.19 15:05, Marek Vasut wrote:
>>>>>> On 5/7/19 11:05 AM, Christoph Muellner wrote:
>>>>>>> Currently addr_aligned() performs an alignment and a length check
>>>>>>> to validate the DMA address. However, some machines have stricter
>>>>>>> restrictions of DMA-able addresses.
>>>>>>>
>>>>>>> This patch adds a call to mach_addr_is_dmaable() to honor this
>>>>>>> machine specific restrictions.
>>>>>>>
>>>>>>> Signed-off-by: Christoph Muellner <christoph.muellner at theobroma-systems.com>
>>>>>>> ---
>>>>>>>
>>>>>>>  common/bouncebuf.c | 6 ++++++
>>>>>>>  1 file changed, 6 insertions(+)
>>>>>>>
>>>>>>> diff --git a/common/bouncebuf.c b/common/bouncebuf.c
>>>>>>> index a7098e2caf..26ddf30ea2 100644
>>>>>>> --- a/common/bouncebuf.c
>>>>>>> +++ b/common/bouncebuf.c
>>>>>>> @@ -26,6 +26,12 @@ static int addr_aligned(struct bounce_buffer *state)
>>>>>>>  		return 0;
>>>>>>>  	}
>>>>>>>  
>>>>>>> +	/* Check if valid DMA address. */
>>>>>>> +	if (!mach_addr_is_dmaable((ulong)state->user_buffer)) {
>>>>>>
>>>>>> Is the cast necessary ?
>>>>>
>>>>> Of course not.
>>>>> Will be fixed in v2.
>>>>>
>>>>> Thanks!
>>>>
>>>> I take that back.
>>>> The cast is needed.
>>>> (And also done several times in this file)
>>>>
>>>> Otherwise you will get:
>>>>
>>>> common/bouncebuf.c: In function ‘addr_aligned’:
>>>> common/bouncebuf.c:35:33: warning: passing argument 1 of ‘mach_addr_is_dmaable’ makes integer from pointer without a cast [-Wint-conversion]
>>>>   if (!mach_addr_is_dmaable(state->user_buffer)) {
>>>>                             ~~~~~^~~~~~~~~~~~~
>>>> In file included from include/common.h:64,
>>>>                  from common/bouncebuf.c:8:
>>>> include/init.h:128:40: note: expected ‘long unsigned int’ but argument is of type ‘void *’
>>>>  int mach_addr_is_dmaable(unsigned long addr);
>>>>                           ~~~~~~~~~~~~~~^~~~
>>>
>>> Shouldn't the function use void __iomem * in the first place ?
>>
>> IMHO Matter of taste.
>> If you prefer it this way, then I can change.
>> Doing grep "unsigned long addr" gave me enough confidence to use that.
>> But I leave this up to you.
> 
> At least that's what Linux uses for mapped addresses.

In Linux two versions of that function are needed: one for phys_addr_t and one for void *.
The linear mapping in U-Boot allows to combine both.
Therefore I see it as a matter of taste.

I will change this to "void __iomem *" and cast to uintptr_t in the rk3399
implementation of that function in a v2 series.