34e1c00a2c
This is the integration of a workaround patch to avoid the serial
tx issues we are seeing on AB testing with the 6.5 kernel. Paul
Gortmaker located a 6.5 series commit that is causing tx to
intermittently stall to serial ports to stall under load.
79a314e29b53 serial-core: disable power managment for serial tx
How to fix it properly with upstream is still and ongoing discussion.
We'll revisit and update this change once something lands in mainline.
The details of the commit are below:
serial-core: disable power managment for serial tx
1% of the time where the getty never appears on ttyS1 even after our
timeout of 1000s.
When this happens we've added code to login to the ttyS0 getty and run
debug commands. We've been able to confirm the getty is running and the
init system doesn't matter (happens with sysvinit and systemd). The
most interesting debug I've seen is this:
root@qemux86-64:~# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:16550A port:000003F8 irq:4 tx:418 rx:43 RTS|CTS|DTR|DSR|CD
1: uart:16550A port:000002F8 irq:3 tx:249 rx:0 RTS|CTS|DTR|DSR|CD
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
root@qemux86-64:~# echo helloA > /dev/ttyS1
root@qemux86-64:~# echo helloB > /dev/ttyS0
helloB
root@qemux86-64:~# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:16550A port:000003F8 irq:4 tx:803 rx:121 RTS|CTS|DTR|DSR|CD
1: uart:16550A port:000002F8 irq:3 tx:281 rx:0 RTS|CTS|DTR|DSR|CD
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
This is being run after the getty didn't appear for 60s on ttyS1 so
we've logged into ttyS0 and run these commands. We've seen that if it
doesn't appear after 60s, it won't appear after 1000s either.
The tx:249 is interesting as it should be tx:273, 273 being the number
of bytes our successful serial getty prompt has. Once we echo something
to the port (8 bytes), tx: jumps to 281, so it suddenly found our
missing login prompt. This is confirmed with the data appearing on the
port after the echo.
I did try disabling the autosuspend code in the commit above but it
made no difference. What does seem to help is changing the conditional
the patch adds around start_tx() back to being under the original
conditions. This is relatively harmless as it will just stop_tx() again
if the xmit buffer is empty and this is a one off operation at probe
time.
The small overhead is much preferred to randomly failing tests.
Discussions with upstream are being attempted:
https://lore.kernel.org/linux-serial/c85ab969826989c27402711155ec086fd81574fb.camel@linuxfoundation.org/T/#t
(From OE-Core rev: 8715d72caa891cd29fd2198da5997d6e6b98fc98)
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Poky
Poky is an integration of various components to form a pre-packaged build system and development environment which is used as a development and validation tool by the Yocto Project. It features support for building customised embedded style device images and custom containers. There are reference demo images ranging from X11/GTK+ to Weston, commandline and more. The system supports cross-architecture application development using QEMU emulation and a standalone toolchain and SDK suitable for IDE integration.
Additional information on the specifics of hardware that Poky supports is available in README.hardware. Further hardware support can easily be added in the form of BSP layers which extend the systems capabilities in a modular way. Many layers are available and can be found through the layer index.
As an integration layer Poky consists of several upstream projects such as BitBake, OpenEmbedded-Core, Yocto documentation, the 'meta-yocto' layer which has configuration and hardware support components. These components are all part of the Yocto Project and OpenEmbedded ecosystems.
The Yocto Project has extensive documentation about the system including a reference manual which can be found at https://docs.yoctoproject.org/
OpenEmbedded is the build architecture used by Poky and the Yocto project. For information about OpenEmbedded, see the OpenEmbedded website.
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Please refer to our contributor guide here: https://docs.yoctoproject.org/dev/contributor-guide/ for full details on how to submit changes.
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As Poky is an integration repository (built using a tool called combo-layer), patches against the various components should be sent to their respective upstreams:
OpenEmbedded-Core (files in meta/, meta-selftest/, meta-skeleton/, scripts/):
- Git repository: https://git.openembedded.org/openembedded-core/
- Mailing list: openembedded-core@lists.openembedded.org
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- Git repository: https://git.openembedded.org/bitbake/
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- Git repository: https://git.yoctoproject.org/cgit/cgit.cgi/meta-yocto
- Mailing list: poky@lists.yoctoproject.org
If in doubt, check the openembedded-core git repository for the content you intend to modify as most files are from there unless clearly one of the above categories. Before sending, be sure the patches apply cleanly to the current git repository branch in question.