# Re: \[PATCH\] Powerpc 8xx CPM\_UART delay in receive

- From: Alan Cox \<hidden\>
- Date: 2012-08-14 14:48:26 
- List: linux-serial
- Page: https://ratatoskr.run/linux-serial/2012/08/3908110
- Thread: https://ratatoskr.run/linux-serial/2012/08/3908106/t.md

```text
On Tue, 14 Aug 2012 16:26:28 +0200
Christophe Leroy [ref] wrote:

> Hello,
> 
> I'm not sure who to address this Patch to either
> 
> It fixes a delay issue with CPM UART driver on Powerpc MPC8xx.
> The problem is that with the actual code, the driver waits 32 IDLE patterns before returning the received data to the upper level. It means for instance about 1 second at 300 bauds.
> This fix limits to one byte the waiting period.

Take a look how the 8250 does it - I think you want to set the value
based upon the data rate. Your patch will break it for everyone doing
high seed I/O.

Alan
```