[U-Boot] [PATH V2] usb: dwc2: invalidate the dcache before starting the DMA

[Kever Yang]

Hi Eddie,


On 04/06/2017 10:14 AM, Marek Vasut wrote:
> On 04/06/2017 04:03 AM, Eddie Cai wrote:
>> We should invalidate the dcache before starting the DMA. In case there are
>> any dirty lines from the DMA buffer in the cache, subsequent cache-line
>> replacements may corrupt the buffer in memory while the DMA is still going on.
>> Cache-line replacement can happen if the CPU tries to bring some other memory
>> locations into the cache while the DMA is going on.
>>
>> Signed-off-by: Eddie Cai <eddie.cai.linux at gmail.com>
>> Reviewed-by: Stefan Brüns <stefan.bruens at rwth-aachen.de>
>> ---
>>   drivers/usb/host/dwc2.c | 19 +++++++++++++------
>>   1 file changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
>> index 5ac602e..e3a5d7d 100644
>> --- a/drivers/usb/host/dwc2.c
>> +++ b/drivers/usb/host/dwc2.c
>> @@ -811,12 +811,19 @@ static int transfer_chunk(struct dwc2_hc_regs *hc_regs, void *aligned_buffer,
>>   	       (*pid << DWC2_HCTSIZ_PID_OFFSET),
>>   	       &hc_regs->hctsiz);
>>   
>> -	if (!in && xfer_len) {
>> -		memcpy(aligned_buffer, buffer, xfer_len);
>> -
>> -		flush_dcache_range((unsigned long)aligned_buffer,
>> -				   (unsigned long)aligned_buffer +
>> -				   roundup(xfer_len, ARCH_DMA_MINALIGN));
>> +	if (xfer_len) {
>> +		if (in) {
>> +			invalidate_dcache_range(
>> +					(unsigned long)aligned_buffer,
>> +					(unsigned long)aligned_buffer +
> Should be uintptr_t all over the place to deal with 32/64 bit systems,
> otherwise great, thanks.
>
>> +					roundup(xfer_len, ARCH_DMA_MINALIGN));
>> +		} else {
>> +			memcpy(aligned_buffer, buffer, xfer_len);
>> +			flush_dcache_range(
>> +					(unsigned long)aligned_buffer,
>> +					(unsigned long)aligned_buffer +
>> +					roundup(xfer_len, ARCH_DMA_MINALIGN));
>> +		}
>>   	}
>>   
>>   	writel(phys_to_bus((unsigned long)aligned_buffer), &hc_regs->hcdma);
>>

Did you test with remove another invalidate_dcache_range() in this function?
I still think no need to have 2 invalidate_dcache in this function.

Thanks,
- Kever
>