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

[Cixi Geng]

>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 .
 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/


Cyril Hrubis <chrubis@suse.cz> 于2020年4月1日周三 上午2:08写道：

> Hi!
> > > Thank you porting the serialcheck.c into LTP
> > > I am sorry to find the serialcheck have not LOOPBACK mode support
> > > the LOOPBACK mode is a better test than HW flow , because most
> machine's
> > > uart have not connect the Rx & TX
> > > in LOOPBACK mode. we test the uart port directly, So we can test one
> uart
> > > port Rx and Tx functions at the same time .
> > > here is the diff  serialcheck with loopback patch
> > > So I'd prefer use loopback mode test the uart in case.
> > > $ diff serialcheck.c serialcheck-with-loopback.c
> >
> > Thanks for the hint, I had no idea that subset serial port hardware has
> > a loopback test that could be enabled in modem control register which is
> > meant for testing. I will have a closer look tomorrow.
>
> 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.
>
> --
> Cyril Hrubis
> chrubis@suse.cz
>
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