[LTP] [PATCH 2/2] device_drivers/uart01: Add uart01 test

[Cixi Geng]

>Indeed but it does not make sense tu run it with a different baud rates,
>since the data are not transmitted at all.
The data exchanged between Tx|Rx and buffer have nothing to do with
baudrate?
I think the baudrate is control Tx|Rx send and receive date rate to|from
buffer.
>Unfortunately it does not seem to work on my AMD based desktop at all,
>my guess is that the loopback bit is silently ignored by the hardware.
>Which means that we cannot enable the test by default in loopback mode
>after all
I will test on my laptop and feedback result today, if it does no work , we
should
check the uart driver what different between x86 and arm64.

Cyril Hrubis <chrubis@suse.cz> 于2020年4月1日周三 下午9:12写道：

> Hi!
> > >If I understand this properly if we set a bit in the modem control
> > >register we will test mostly the circuits between CPU and UART
> > >controller which is better than nothing, but we are not really testing
> > >if the port speed was set correctly since the data are just being copied
> > >between registers in the UART controller, so it does not make sense to
> > >change the speed in this mode. Or am I mistaken?
> >
> > >Also it does not seem to work for me and I've tried with both serial
> > >ports on my desktop PC as well as with USB-to-Serial dongle. I can set
> > >the bit just fine but loopback does not work.
> >
> > In the loopback mode , the data will be transferred in buffer ,and back
> to
> > CPU
> > by FIFO way.
> > I understand the test flow is CPU->uart Tx-> buffer file->uart Rx->CPU,
> > so it does make sense to the uart driver .
>
> Indeed but it does not make sense tu run it with a different baud rates,
> since the data are not transmitted at all.
>
> >  BTW??? I found the latest seriacheck git is
> > https://github.com/nsekhar/serialcheck.git
> > and I test on my arm64 machine of sprdtream. and it does works.
> > the test log I had send in another patch
> > https://patchwork.ozlabs.org/patch/1264553/
>
> Unfortunately it does not seem to work on my AMD based desktop at all,
> my guess is that the loopback bit is silently ignored by the hardware.
>
> Which means that we cannot enable the test by default in loopback mode
> after all.
>
> --
> Cyril Hrubis
> chrubis@suse.cz
>
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