[U-Boot] [PATCH] mtd: nand: mxs: fix cache alignment for cache lines >32

[Stefan Agner]

On 2016-08-03 06:51, Fabio Estevam wrote:
> On Tue, Aug 2, 2016 at 3:55 AM, Stefan Agner <stefan at agner.ch> wrote:
>> From: Stefan Agner <stefan.agner at toradex.com>
>>
>> Currently the command buffer gets allocated with a size of 32 bytes.
>> This causes warning messages on systems with cache lines bigger than
>> 32 bytes:
>> CACHE: Misaligned operation at range [9df17a00, 9df17a20]
>>
>> Define command buffer to be at least 32 bytes, but more if cache
>> line is bigger.
>>
>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>> ---
>> This appeared after Simon enable the message in check_cache_range
>> by default...
> 
> On mx6ul pico I also get similar warnings even though NAND is not used
> on this board:
> 
> U-Boot 2016.09-rc1-00245-gad6a303 (Aug 03 2016 - 10:31:52 -0300)
> 
> CPU:   Freescale i.MX6UL rev1.0 at 396 MHz
> Reset cause: WDOG
> Board: PICO-IMX6UL-EMMC
> I2C:   ready
> DRAM:  256 MiB
> CACHE: Misaligned operation at range [8fff0000, 8fff0004]
> CACHE: Misaligned operation at range [8fff0024, 8fff0028]
> PMIC: PFUZE3000 DEV_ID=0x30 REV_ID=0x11
> MMC:   FSL_SDHC: 0
> *** Warning - bad CRC, using default environment
> 
> In:    serial
> Out:   serial
> Err:   serial
> Net:   FEC
> Hit any key to stop autoboot:  0
> 
> Looks like we need a more generic fix?

As you noted, this particular case is due to cache flush of the page
table and should be fixed with:
arm: cache: always flush cache line size for page table

Afaik, there is no such thing as a generic fix for cache line alignment
issues... Every call site need to make sure to keep data cache line
aligned, especially in case a external device (DMA) are modifying the
same data...

--
Stefan