[U-Boot] [PATCH 1/3] MIPS: Move cache sizes to Kconfig

[Marek Vasut]

On 05/27/2016 05:43 PM, Daniel Schwierzeck wrote:
> 
> 
> Am 27.05.2016 um 16:40 schrieb Marek Vasut:
>> On 05/27/2016 04:34 PM, Paul Burton wrote:
>>> On Fri, May 27, 2016 at 04:32:26PM +0200, Marek Vasut wrote:
>>>> On 05/27/2016 12:36 PM, Paul Burton wrote:
>>>>> On Thu, May 26, 2016 at 06:10:38PM +0200, Marek Vasut wrote:
>>>>>>> diff --git a/arch/mips/lib/cache.c b/arch/mips/lib/cache.c
>>>>>>> index 7482005..7695325 100644
>>>>>>> --- a/arch/mips/lib/cache.c
>>>>>>> +++ b/arch/mips/lib/cache.c
>>>>>>> @@ -9,7 +9,7 @@
>>>>>>>  #include <asm/cacheops.h>
>>>>>>>  #include <asm/mipsregs.h>
>>>>>>>  
>>>>>>> -#ifdef CONFIG_SYS_CACHELINE_SIZE
>>>>>>> +#if CONFIG_SYS_CACHELINE_SIZE != 0
>>>>>>
>>>>>> Wouldn't it make more sense to introduce something like
>>>>>> CONFIG_HAVE_CACHE_SUPPORT instead , so you don't need this
>>>>>> #if CONFIG_FOO != 0 construct all over the place ?
>>>>>
>>>>> Hi Marek,
>>>>>
>>>>> It's not about whether cache support is present (we always build cache
>>>>> support), it's about whether we are hardcoding the sizes of the caches
>>>>> or detecting them at runtime. The latter is especially useful on
>>>>> FPGA-based platforms like Malta where the CPU (& caches) can change. I
>>>>> suppose I could add something like CONFIG_SYS_CACHE_SIZE_AUTO, but I
>>>>> still think it would be cleanest to have that default to a value based
>>>>> upon whether a board has set a non-zero size for any of the caches.
>>>>
>>>> Auto-detecting cacheline size is cool, but that'd need much more work.
>>>> Just grep through drivers/ for CONFIG_SYS_CACHELINE_SIZE and you'll
>>>> see a lot of code depends on non-zero value in it. Setting it to zero
>>>> will just bite you at some point in a nasty way.
>>>
>>> Hi Marek,
>>
>> Hi!
>>
>>> We're already using the cache size auto-detection on Malta, and on 2
>>> other FPGA-based boards internally. I've submitted v2 which preserves
>>> CONFIG_SYS_CACHELINE_SIZE as a synonym of ARCH_DMA_MINALIGN for the
>>> drivers that are still using it.
>>
>> That's a good workaround for now. Would you be interested in fixing this
>> runtime cache configuration properly ?
>>
> 
> there is no runtime configuration for ARCH_DMA_MINALIGN. This value is
> defined at compile-time by Kconfig option MIPS_L1_CACHE_SHIFT. This is
> similar to what Linux is doing.
> 
So the DMA_MINALIGN is always a multiple of cacheline size on MIPS ?

-- 
Best regards,
Marek Vasut