> From: Paul Menzel <pmenzel@xxxxxxxxxxxxx> > Sent: Friday, February 10, 2023 6:35 PM > > Dear Chia-Wei, > > > Thank you for your patch. > > Am 10.02.23 um 08:26 schrieb Chia-Wei Wang: > > Add the driver for Aspeed UART/VUART devices, which are 16550A > > compatible. It is an wrapper to cover the generic 16550A operation > > a wrapper > > > while exetending DMA feature for the devices. > > extending > > Is this for all ASPEED devices or only current ones? There is major design change of UDMA. Therefore, this patch is for AST2600 only. > > How did you test this? What is the maximum transfer speed? Yes. I can't remember the precise data. The experiment was done like 2 years ago. But it should be above 2MB/s > > There are other serial drivers also supporting DMA, and those seem to use > DMAengine? > > $ git grep dmaengine drivers/tty/serial/8250/ > Yes. The UDMA design is dedicated to, and tightly coupled with each UART/VUART devices. And UDMA does not support common DMA control such as suspend/resume. We found certain discussions in the old mailing list saying that if a DMA controller is not fully fit into the DMAEngine subsystem, placing the implementation in the soc folder might be an option. Regards, Chiawei
