Messages in this thread | | | From | Kuninori Morimoto <> | Subject | Re: [PATCH v3] dmaengine: rcar-dmac: use TCRB instead of TCR for residue | Date | Mon, 6 Nov 2017 01:24:33 +0000 |
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Hi Geert
> Large serial console input (copy and pasting long lines) works, as that uses > DMA. Small serial console input (typing) doesn't work. > > Apparently for the serial port, TCR contains the value we need (< 0x20), > while TCRB always contains 0x20. > Perhaps the code should use the minimum of both registers instead?
TCR(= read) happen 1st, and TCRB (= write) happen next. "TCRB always contains 0x20" means, DMA didn't transfer data for some reason ?
"use minimum" idea can't guarantee data transfering, same as previous topic I guess.
Best regards --- Kuninori Morimoto
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