[PATCH linux dev-4.7 09/12] mtd: spi-nor: aspeed: add DMA support to smc controller

[Cédric Le Goater]

On 10/17/2016 07:03 AM, Joel Stanley wrote:
> On Fri, Oct 14, 2016 at 11:08 PM, Cédric Le Goater <clg at kaod.org> wrote:
>> The Aspeed FMC controller can handle transfers to the flash modules
>> using DMAs. A couple of registers first need to be programmed with the
>> DRAM and flash addresses and the length of the transfer. The transfer
>> is then initiated using a DMA control register and an interrupt
>> notifies the completion.
>>
>> Such transfers can replace the current IO mode in the read/write ops
>> when some conditions are met on the size and the alignment. In case of
>> failure, a timeout for instance, the operation is restarted using the
>> IO mode.
>>
>> DMA support does not seem to be that efficient. So we provide some
>> sysfs files for tuning and to switch it on and off (default is off)
> 
> It looks like this version only has a module parameter, and not the sysfs files.

Ah ? I have these :

	/sys/module/aspeed_smc/parameters/dma_timeout
	/sys/module/aspeed_smc/parameters/min_dma_size
	/sys/module/aspeed_smc/parameters/use_dma

which we can control with the kernel command line at boot  : 

	"aspeed_smc.use_dma=1"

Is there an other API ? 

Thanks,

C.