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

[Marek Vasut]

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);
> 


-- 
Best regards,
Marek Vasut