4.16 OMAP serial transmit corruption?

[Vignesh R]

On Monday 16 April 2018 09:15 PM, Tony Lindgren wrote:
> * Russell King - ARM Linux <linux at armlinux.org.uk> [180416 15:19]:
>> Hi,
>>
>> I'm not entirely sure what's going on, but I see corrupted characters
>> with the serial console on the OMAP4430 SDP board.  During boot,
>> everything seems fine, the problem appears to be userspace output.
>>
>> For example, if I edit a file, then quit vi:
>>
>> :q■■%■■B■■Z■root at omap-4430sdp:~#
> 
> I don't think I've seen that one. What I've seen few times is
> typing a key on the serial console echoing back the previous
> character typed while the new character won't get displayed
> until hitting keyboard again. Only rebooting the device seems
> to solve this. This is with 4430 ES2.3 revision.
> 
> I wonder if we're missing some parts of errata i202 handling
> in omap_8250_mdr1_errataset()?
> 
> Also, I'm seeing an issue where the UARTs won't idle on init
> with 8250_omap driver if connected to the wl12xx bluetooth port
> unless I write some data to the port first. It does not seem
> to be related to the rts/cts lines being wired as I've tested
> muxing them out of the way.
> 

If this instance of UART is using DMA then it might be due an errata
worked around in AM33/AM43/DRA7:
https://patchwork.kernel.org/patch/6784331/


-- 
Regards
Vignesh