Hi Dirk-san,
> From: Dirk Behme, Sent: Friday, April 12, 2019 2:29 PM
>
> From: Achim Dahlhoff <Achim.Dahlhoff@xxxxxxxxxxxx>
>
> The tx_status poll in the rcar_dmac driver reads the status register
> which indicates which chunk is busy (DMACHCRB). Afterwards the point
> inside the chunk is read from DMATCRB. It is possible that the chunk
> has changed between the two reads. The result is a non-monotonous
> increase of the residue. Fix this by introducing a 'safe read' logic.
>
> Fixes: 73a47bd0da66 ("dmaengine: rcar-dmac: use TCRB instead of TCR for residue")
I guess this driver has this issue potencially from previous of the commit
(maybe commit ccadee9b1e9 ("dmaengine: rcar-dmac: Implement support for hardware descriptor lists"?).
But, this patch seems good to fix the issue.
So,
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Best regards,
Yoshihiro Shimoda
