[U-Boot] [PATCH] blk: Remove various places that do flush cache after read

[Bin Meng]

Hi York,

On Wed, Aug 23, 2017 at 12:49 AM, York Sun <york.sun at nxp.com> wrote:
> On 08/21/2017 08:42 PM, Bin Meng wrote:
>> All these places seem to inherit the codes from the MMC driver where
>> a FIXME was put in the comment. However the correct operation after
>> read should be cache invalidate, not flush.
>>
>> The underlying drivers should be responsible for the cache operation.
>> Remove these codes completely.
>>
>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>> ---
>>
>>   arch/arm/cpu/armv8/fsl-layerscape/ppa.c | 15 ---------------
>>   board/toradex/common/tdx-cfg-block.c    |  2 --
>>   cmd/mmc.c                               |  2 --
>>   drivers/block/blk-uclass.c              |  3 ---
>>   drivers/block/blk_legacy.c              |  3 ---
>>   drivers/net/fm/fm.c                     |  2 --
>>   drivers/net/phy/cortina.c               |  2 --
>>   drivers/qe/qe.c                         |  2 --
>>   8 files changed, 31 deletions(-)
>>
>> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/ppa.c b/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
>> index 24ddb5d..bbf8bba 100644
>> --- a/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
>> +++ b/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
>> @@ -107,9 +107,6 @@ int ppa_init(void)
>>               return -EIO;
>>       }
>>
>> -     /* flush cache after read */
>> -     flush_cache((ulong)fitp, cnt * 512);
>> -
>
> NACK here.
>
>
>>       ret = fdt_check_header(fitp);
>>       if (ret) {
>>               free(fitp);
>> @@ -134,9 +131,6 @@ int ppa_init(void)
>>       }
>>       debug("Read PPA header to 0x%p\n", ppa_hdr_ddr);
>>
>> -     /* flush cache after read */
>> -     flush_cache((ulong)ppa_hdr_ddr, cnt * 512);
>> -
>>       ppa_esbc_hdr = (uintptr_t)ppa_hdr_ddr;
>>   #endif
>>
>> @@ -164,9 +158,6 @@ int ppa_init(void)
>>               return -EIO;
>>       }
>>
>> -     /* flush cache after read */
>> -     flush_cache((ulong)ppa_fit_addr, cnt * 512);
>> -
>>   #elif defined(CONFIG_SYS_LS_PPA_FW_IN_NAND)
>>       struct fdt_header fit;
>>
>> @@ -208,9 +199,6 @@ int ppa_init(void)
>>       }
>>       debug("Read PPA header to 0x%p\n", ppa_hdr_ddr);
>>
>> -     /* flush cache after read */
>> -     flush_cache((ulong)ppa_hdr_ddr, fw_length);
>> -
>>       ppa_esbc_hdr = (uintptr_t)ppa_hdr_ddr;
>>   #endif
>>
>> @@ -232,9 +220,6 @@ int ppa_init(void)
>>                      CONFIG_SYS_LS_PPA_FW_ADDR);
>>               return -EIO;
>>       }
>> -
>> -     /* flush cache after read */
>> -     flush_cache((ulong)ppa_fit_addr, fw_length);
>>   #else
>>   #error "No CONFIG_SYS_LS_PPA_FW_IN_xxx defined"
>>   #endif
>
> Hold on for ppa.c. We need to flush the cache after reading PPA image
> and it header after loading. These images need to be flushed into main
> memory. I will need to confirm with our team if we can remove flushing here.
>

For the first 3 parts in this ppa.c file, I see they are all reading
PPA image from MMC while MMC driver is using DMA so this is wrong (as
I mentioned in the commit message I suspect they are all copy/paste
from the MMC driver).

The only questionable change is the last one which is reading
something from NAND and if NAND driver is not using DMA, that cache
flush is needed as you pointed out.

Regards,
Bin