Hi Marek,
On 04/06/2017 06:20 PM, Marek Vasut wrote:
On 04/06/2017 10:34 AM, Kever Yang wrote:
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.li...@gmail.com>
Reviewed-by: Stefan Brüns <stefan.bru...@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.
You need the first invalidate to prevent having data stuck in the cache
and accidentally being evicted into the RAM while the USB DMA is also
running , thus creating a total mess of the result.
Yes, I'm very clear about what happen here, because it's me report
the origin bug.
What I mean is the fix should be _move_ the invalidate_dcache_range()
operation
from "after start DMA transfer" to "before DMA transter" for in
transfer, but not
_add_ a invalidate_dcache_range() operation.
If you apply this patch, then there will be two
invalidate_dcache_range() operation
for in transfer, and the second one is no need, because CPU should not
have any
access to the buffer during dma start and done.
Thanks,
- Kever
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