<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jul 26, 2015 at 5:02 PM, AYAN KUMAR HALDER <span dir="ltr"><<a href="mailto:ayankumarh@gmail.com" target="_blank">ayankumarh@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
I am doing a DMA transfer (to device) using pl330 driver from<br>
memory(DDR) to device(m25p80, spi- nor). I am sending data in chunks<br>
of 256 bytes ( m25p80 - writesize) using scatter-gather mechanism.<br>
<br>
I see that when I try to write 8K of data, one or the other 256<br>
bytes(or lesser) are not written or are partially written with 0s.<br>
<br>
This problem is observed only when I perform a to-device DMA transfer.<br>
When I perform a from-device DMA transfer, I am able to read correct<br>
data.<br>
<br></blockquote><div> </div><div>There could be multiple issues like </div><div>- In buffers allocations, is the buffer used for to-device DMA is physically contiguous?</div><div>- Caching issue, buffer should be un-cacheable.</div><div>- Any other programming error.</div><div> </div><div>- Chetan Nanda</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Regards,<br>
Ayan Kumar Halder<br>
<br>
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