On 17/08/2020 17:20, Luis Chamberlain wrote:
On Fri, Aug 14, 2020 at 11:59:36PM +0200, Lukas Middendorf wrote:
On 14/08/2020 18:37, Luis Chamberlain wrote:
On Fri, Aug 14, 2020 at 01:38:40PM +0200, Lukas Middendorf wrote:
If the firmware is *not* present for the si2168 driver and the device
has *not* been used yet you get a system freeze which you cannot recover
from, but only if you are *not* using a driver which also caches its
firmware already?
Yes, this is exactly what I wanted to say.
OK great.. but..
A new installation of Fedora 32 without firmware files
Fedora 32 comes with no firmware at all? Are you sure? How about your
wifi?
Fedora does come with firmware files for many devices (wifi, nouveau, …) but
not for dvb devices. Firmware for the si2168 has to be installed as an extra
package dvb-firmware from rpmfusion. When I talk about "no firmware files"
or "install the firmware files" I mean the si2168 (and other dvb hardware)
firmware files only. The nouveau firmware files are always present.
OK so how do you know that other firmware is not getting loaded or cached?
dmesg with firmware_class debug output enabled
Other than checking kernel logs you can rm -rf /lib/firmware/ and then
only place the files you want to test.
and with nouveau did
not show my freeze problem. Installing either the firmware files or the
nvidia driver started the freeze during resume.
Here now you say that if you install either the firmware files for
either si2168 or nouveau can cause a freeze,
no, I'm talking just about the firmware files for si2168
OK so if you install the firmware files of si2168 you do run into a
freeze, and this freeze happens on resume from suspend?
Without the si2168 firmware the freeze does not happen.
Is that right?
In the case that I *don't* have the firmware files for si2168 (!) present it
happens only if no other firmware is cached on suspend (in my case by the
nouveau driver). No statement made about cases where the si2168 firmware
file is present.
OK this statement is clear and is very different from the one I made
above.
But note, that this is true, how are you *sure* that no other firmware
other than nouveau is being used? What about wifi? or bluetooth?
I don't have wifi or bluetooth enabled in the BIOS. If I don't use the
nouveau driver, "dmesg | grep firmware" is completely empty after boot
except for the kernel command line part "ddebug_query=module
firmware_class +pmf". After suspend + resume I just get two lines for
the calls to cache and uncache firmwares. If any other firmware is used,
it is apparently not using the standard firmware loader.
If I rename the directory /usr/lib/firmware everything seems to work as
before (nouveau and si2168 not loaded) and I don't see any complaints
about missing firmware in dmesg.
If I enable my secondary rtl8125 Ethernet controller in the BIOS (I only
tested this now, I always had it disabled previously), I can see its
firmware being loaded on boot and cached on suspend. This then has an
effect on my freeze problem identical to using the nouveau driver.
You also clarify here your freeze happens on resume only. Is that right?
Never on suspend, but if the freeze happens, it happens only on resume?
Correct. I have not seen a freeze on suspend. It only happens on resume.
OK this is only if and only if you haven't used the si2168 device,
right? And since this is related to si2168 we know that even if you
don't use the si2168 device its function which calls to load firmware
*does* get called on resume, even though that same function was not
called on probe, as the device is not used.
If true, then the race to freeze here happens on resume against btrfs.
And is the firmware present or not in this case, in which the freeze
happens?
A freeze can happen on resume with and without the si2168 firmware files
installed. It however is easier to hit the freeze with the firmware
files installed. Without the firmware files present the freeze happens
only if no other driver uses the firmware loader.
The actual case where you reach a freeze is still not clear yet. Let's
try to clarify this.
OK, let's try that again. To freeze during resume all of 1-4 has to be true:
1. /usr/lib/firmware is on btrfs
2. my Hauppauge WinTV-dualHD USB DVB tuner (contains si2168) is connected
3. have not actively used the tuner
4. any of the following cases:
4a) si2168 firmware not installed + nouveau driver not used + have not run
"ls -R /usr/lib/firmware" before suspend
4b) firmware file installed + not run "cat /usr/lib/firmware/dvb*"
4c) firmware file installed + not run "ls -R /usr/lib/firmware" + not
nouveau driver
OK perfect, now the next question to clarify is *are you sure* that no
other firmware is used, other than si2168 and nouveau?
I'm totally sure that no other firmware is used through the standard
firmware loader. I'm also almost sure that no firmware from
/usr/lib/firmware is used though any other means.
Not leading to a freeze is:
A: si2168 firmware not installed + nouveau driver used
B: si2168 firmware not installed + run "ls -R /usr/lib/firmware" before
suspend
C: used the tuner before suspend (or tried to use, in case that the si2168
firmware is not installed)
D: using my patches with firmware_request_cache()
E: si2168 firmware installed + "ls -R /usr/lib/firmware" + "cat
/usr/lib/firmware/dvb*"
F: si2168 firmware installed + nouveau driver used + "cat
/usr/lib/firmware/dvb*"
I verified all cases again to make sure I was not remembering anything
wrong.
This helps, thanks so much, now we'll have to write a reproducer, thanks
for the report!!
Will you do it yourself or do you expect me to do anything for this?
The nouveau driver in use seems to be equivalent to running "ls -R
/usr/lib/firmware" before suspend.
All the cases seem to boil down to:
It freezes if the file system has to be accessed to list the content of
/usr/lib/firmware or to read the si2168 firmware file
Let's confirm first whether or not your system is using other firmware
files too or not.
I confirmed that above. Why is this so important, anyway?
Lukas
