RE: [PATCH V1] serial: imx: revert setup DCEDTE early and ensure DCD and RI irqs to be off

Hi Fabio,

On 23 May 2017 17:26 Fabio Estevam wrote:

Subject: Re: [PATCH V1] serial: imx: revert setup DCEDTE early and ensure DCD and RI irqs to be off
On Tue, May 23, 2017 at 9:17 AM, Steve Twiss wrote:

quoted

Revert the commit e61c38d85b7392e ("serial: imx: setup DCEDTE early and
ensure DCD and RI irqs to be off")

The patch submitted to setup DCEDTE early and ensure DCD and RI irqs to
be off, causes a serial console display problem the i.MX6Q SABRESD board.
The console becomes unreadable and unwritable.

Tested-by: Steve Twiss <redacted>
Signed-off-by: Steve Twiss <redacted>

---
This patch applies against linux-next and v4.12-rc2

Hi,

I have been seeing a problem with the serial output console on the i.MX6Q
SABRESD, but not the i.MX6DL SABRESD. Everything was fine up to
linux-mainline/v4.11 but changed after linux-next/next-20170501.

Some bisection has pointed at the commit
e61c38d85b7392e033ee03bca46f1d6006156175 which, once removed from my
linux-next/v4.12-rc2 build allows the i.MX6Q board to display the console
correctly again.

This patch removes the original commit e61c38d85b7392e ("serial: imx:
setup DCEDTE early and ensure DCD and RI irqs to be off") from  linux-next
v4.12-rc2 and fixes the serial problem seen in the i.MX6Q SABRESD board.

How can the error be reproduced?

Care to share more details of the error, please?

The USB to UART connection gets corrupted.
If this patch is applied to the kernel, the i.MX6 Q (quad), and only this board as far as
we know, starts to fail. This does *not* change the i.MX6DL and other sabre boards
have been tested on kernelci.org and do not see a problem.

An NXP/Freescale SABRESD i.MX6 Q board is requred.

My system for testing is to TFTP the Linux kernel over an ethernet connection. The
U-boot executes okay and the UART is working at that point. When the kernel loads
the console trace becomes garbled, in the sense that I get the some characters being
output to the console, in the style of the kernel starting up, but they are not correct.

I expect the kernel has started ok, but I am unable to read/write through the UART
console because of corruptions.

Console log with the output I am seeing with linux-next/v4.12-rc2

--- 8< ---

U-Boot 2009.08-00001-gf65536a (Jan 12 2015 - 15:47:19)

CPU: Freescale i.MX6 family TO1.2 at 792 MHz
Thermal sensor with ratio = 200
Temperature:   46 C, calibration data 0x5f15527d
mx6q pll1: 792MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock     : 66000000Hz
ipg per clock : 66000000Hz
uart clock    : 80000000Hz
cspi clock    : 60000000Hz
ahb clock     : 132000000Hz
axi clock   : 264000000Hz
emi_slow clock: 132000000Hz
ddr clock     : 528000000Hz
usdhc1 clock  : 198000000Hz
usdhc2 clock  : 198000000Hz
usdhc3 clock  : 198000000Hz
usdhc4 clock  : 198000000Hz
nfc clock     : 24000000Hz
Board: i.MX6Q-SABRESD: unknown-board Board: 0x63012 [WDOG ]
Boot Device: SD
I2C:   ready
DRAM:   1 GB
MMC:   FSL_USDHC: 0,FSL_USDHC: 1,FSL_USDHC: 2,FSL_USDHC: 3
In:    serial
Out:   serial
Err:   serial
Found PFUZE100! deviceid=10,revid=11
Net:   got MAC address from IIM: 00:04:9f:02:e3:0a
FEC0 [PRIME]
Hit any key to stop autoboot:  0
PHY indentify @ 0x1 = 0x004dd074
FEC: Link is Up 796d
Using FEC0 device
TFTP from server 192.168.2.1; our IP address is 192.168.2.2
Filename 'uImage_dtb.imx6q.v4.12-rc2'.
Load address: 0x12000000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ##########################################################
done
Bytes transferred = 5951108 (5ace84 hex)
## Booting kernel from Legacy Image at 12000000 ...
   Image Name:
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    5951044 Bytes =  5.7 MB
   Load Address: 10800000
   Entry Point:  10800000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK
OK

Starting kernel ...

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--- 8< ---

Is this enough information for you?
It would be difficult to reproduce without the i.MX6Q (quad) board from Freescale/NXP
I think.

Regards,
Steve