Re: [PATCH] Revert "serial: amba-pl011: fix incorrect integer size in pl011_fifo_to_tty()"

[Timur Tabi <timur@codeaurora.org>]

On 10/23/2015 11:02 AM, Dave P Martin wrote:
> I'm pretty sure CREAD should default to enabled[1], and that usually
> software won't modify it.
>
> Assuming that this is indeed the problem, it's possible that another bug
> in the pl011 driver is wrongly clearing this flag.  Sadly I don't have
> time to look at the code again just now ...:(

Perhaps, but !CREAD is definitely broken without this patch.  So if the 
driver really is clearing CREAD somewhere else, then that's where the 
real bug is.

>
> Could be interesting to stick some BUG_ON(!CREAD) in the driver to
> try and track down where that's coming from.

CREAD is disabled by default when opening the console.  You need to 
explicitly set it in the termios structure.  I can easily believe that 
Huang's rootfs is just forgetting to set that bit because for the last 
five years, it didn't matter.

Huang,

In the beginning of pl011_set_termios() and sbsa_uart_set_termios(), 
please add this code:

	BUG_ON(!(termios->c_cflag & CREAD));		

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.