[U-Boot] [PATCH] arm: cache: always flush cache line size for page table

[Marek Vasut]

On 08/02/2016 07:01 PM, Stefan Agner wrote:
> On 2016-08-02 08:56, Marek Vasut wrote:
>> On 08/02/2016 05:47 PM, Stefan Agner wrote:
>>> On 2016-08-02 02:38, Marek Vasut wrote:
>>>> On 08/02/2016 09:07 AM, Stefan Agner wrote:
>>>>> From: Stefan Agner <stefan.agner at toradex.com>
>>>>>
>>>>> The page table is maintained by the CPU, hence it is safe to always
>>>>> align cache flush to a whole cache line size. This allows to use
>>>>> mmu_page_table_flush for a single page table, e.g. when configure
>>>>> only small regions through mmu_set_region_dcache_behaviour.
>>>>>
>>>>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>>>>> ---
>>>>> This avoids two messages observed on a i.MX 7 based system:
>>>>> CACHE: Misaligned operation at range [9fff0000, 9fff0004]
>>>>> CACHE: Misaligned operation at range [9fff0024, 9fff0028]
>>>>>
>>>>> Those were caused by two calls to mmu_set_region_dcache_behaviour
>>>>> in arch/arm/imx-common/cache.c (enable_caches).
>>>>>
>>>>> Not sure if this is the right way to fix this... Also, we could
>>>>> do the alignment in mmu_set_region_dcache_behaviour.
>>>>
>>>> This should be fixed on the driver level indeed, not in cache_v7.c
>>>
>>> Fixing it in enable_caches in arch/arm/imx-common/cache.c is definitely
>>> unpractical...
>>>
>>> So I guess by driver level you mean in
>>> arch/arm/lib/cache-cp15.c:mmu_set_region_dcache_behaviour
>>> correct?
>>>
>>> It has the potential to code duplication in case other users of
>>> mmu_page_table_flush need to flush page tables less than cache line
>>> size...
>>
>> Isn't the function supposed to flush the whole MMU table ? Or is the
>> idea here to really flush separate entries ?
> 
> It has a start/stop argument, so I guess it is supposed to flush
> separate
> entries...

The cache ops also have start/stop argument, but they explicitly cannot
be used on non-cache-aligned addresses, so the start/stop argument does
not imply anything.

-- 
Best regards,
Marek Vasut