On 03/01/2018 02:36 AM, Bartosz Golaszewski wrote:
2018-02-28 22:40 GMT+01:00 David Lechner <david@xxxxxxxxxxxxxx>:
On 02/28/2018 06:38 AM, Bartosz Golaszewski wrote:
I think I found the reason for the strange crashes we were
experiencing (emac core->name being NULL) thanks to Sekhar who pointed
me in the right direction.
The mdio driver fails to probe with v7 due to the supplied clock rate
being wrong. Before failing we register the emac clock with
pm_clk_add_clk(). When clock_ops puts the clock, it decreases the
reference count of the clock, but we never actually increased it in
the first place in the line above. The core clock code then destroys
the associated clk_core structure. When the next user comes around (in
our case the clk debug functions) the system crashes.
I believe there to be two issues: one is with v7 - we need to increase
the clock reference count in davinci_psc_genpd_attach_dev().
Second is the error path in the clock framework - we should remove the
destroyed clk_core from the debug list, which is not being done now.
Why we even need to track the refcount of clk_core is a mistery for me
though. Stephen, Mike?
Best regards,
Bartosz Golaszewski
Great find. I figured it had to be something like this, but I wasn't
able to reproduce the problem yet.
I suppose it is time to spin up a v8 with some fixes.
I still don't know why the mdio clock rate is much lower than in
mainline though. Any ideas?
Thanks,
Bart
Now that you have fixed the crash, can you answer the questions I have
asked earlier?
Can you post the output of this command so that I can see how your
clocks are setup:
cat /sys/kernel/debug/clk/clk_summary
Using your workaround, can you run:
cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
If you see:
1e27000.clock-controller: emac off-0
then genpd is not working like it is supposed to. You should see something
like this for device that are working:
1e27000.clock-controller: uart2 on
/devices/platform/soc@1c00000/1d0d000.serial active
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
