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

From: Giulio Benetti
Date: Mon Jun 04 2018 - 06:50:57 EST


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

I've checked on Synopsis Designware 8250 datasheet and it's not supported.
Here is datasheet I went through:

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

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