RE: [v2,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst

EnDe Tan
2023-11-06T08:44:07Z

> Are client drivers setting this today, will there be regression if not set?
I don't see any dw-axi-dmac client driver setting this src_maxburt/dst_maxburst explicitly.
This means that all the while, those client drivers have been using the default value of DWAXIDMAC_BURST_TRANS_LEN_4.
In the patch, to maintain this backward compatibility, ternary operator is used, for example:
> > + dst_burst_trans_len = chan->config.dst_maxburst ?
> > + __ffs(chan->config.dst_maxburst) - 1 :
> > + DWAXIDMAC_BURST_TRANS_LEN_4;
so that if src_maxburst/dst_maxburst is not set, default value of DWAXIDMAC_BURST_TRANS_LEN_4 applies.

> this is wrong, memcpy should never use slave config value. These values are
> for peripheral and not meant for mem-mem transfers
Agreed, thanks for pointing that out. It shall be removed in patch v3.