Re: [PATCH 4/8] serial: 8250: Handle case port doesn't have TEMT interrupt using em485.

[Giulio Benetti]

Hi,

Il 04/06/2018 12:17, Andy Shevchenko ha scritto:
> On Fri, 2018-06-01 at 14:40 +0200, Giulio Benetti wrote:
> > Some 8250 ports only have TEMT interrupt, so current implementation
> > can't work for ports without it. The only chance to make it work is to
> > loop-read on LSR register.
> >
> > With NO TEMT interrupt check if both TEMT and THRE are set looping on
> > LSR register.
>
> > --- a/drivers/tty/serial/8250/8250_dw.c
> > +++ b/drivers/tty/serial/8250/8250_dw.c
>
> > -		int ret = serial8250_em485_init(up);
> > +		int ret = serial8250_em485_init(up, false);
>
> Is true for all possible DW configured types? Or it's your particular
> case?

I've checked on Synopsis Designware 8250 datasheet and it's not supported.
Here is datasheet I went through:
https://linux-sunxi.org/images/d/d2/Dw_apb_uart_db.pdf

There seems not to be TEMT interrupt, I use it under sunxi SoC and on 
their datasheet(A20 for example), they don't report that interrupt too.
So it seems to be valid for all DW configured types, anyway I don't know 
how many IP reviews there could be of that peripheral.
I've tried to subscribe at Synopsis to obtain latest Datasheet but it 
ask me an active ID I don't have.

--
Giulio Benetti
CTO

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