[U-Boot] [PATCH 3/6] sf: sf_ops: use dma to copy data from mmap region if platform supports

[Mugunthan V N]

On Wednesday 02 December 2015 03:24 AM, Simon Glass wrote:
> Hi,
> 
> On 1 December 2015 at 04:13, Mugunthan V N <mugunthanvnm at ti.com> wrote:
>> Add dma memcpy api to the default spi_flash_copy_mmap(), so that
>> dma will be used to copy data when DM_DMA is defined for the
>> platform.
>>
>> Signed-off-by: Mugunthan V N <mugunthanvnm at ti.com>
>> ---
>>  drivers/mtd/spi/sf_ops.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
>> index 3a56d7f..3c83f8a 100644
>> --- a/drivers/mtd/spi/sf_ops.c
>> +++ b/drivers/mtd/spi/sf_ops.c
>> @@ -16,6 +16,7 @@
>>  #include <watchdog.h>
>>  #include <linux/compiler.h>
>>  #include <linux/log2.h>
>> +#include <dma.h>
>>
>>  #include "sf_internal.h"
>>
>> @@ -389,6 +390,10 @@ int spi_flash_read_common(struct spi_flash *flash, const u8 *cmd,
>>
>>  void __weak spi_flash_copy_mmap(void *data, void *offset, size_t len)
>>  {
>> +#ifdef CONFIG_DM_DMA
>> +       if (!dma_memcpy(data, offset, len))
>> +               return;
>> +#endif
>>         memcpy(data, offset, len);
>>  }
>>
>> --
>> 2.6.3.368.gf34be46
>>
> 
> This looks like one driver (SPI flash) calling a weak function in
> another (SPI). Why isn't this done with the driver interface?
> 

This is suppose to be with SPI flash driver, as the flash driver can
only decide whether to use memory map transfers or spi transfers.

It was kept as a weak function so that platforms with DMA support can
have their own spi_flash_copy_mmap() to transfer data with DMA support.
But for some reasons this implementations landed in spi driver files
which is not the best place, it should have to be done in DMA drivers.

With CONFIG_DMA, this should go away with the above #ifdef CONFIG_DMA
and the weak function attribute can be removed later.

Regards
Mugunthan V N