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SubjectRe: [tip: timers/core] clocksource/drivers/timer-probe: Avoid creating dead devices

Hi Saravana,

On 25/03/2020 23:56, Saravana Kannan wrote:
> On Wed, Mar 25, 2020 at 2:47 PM Thomas Gleixner
> <> wrote:
>> Saravana Kannan <> writes:
>>> On Tue, Mar 24, 2020 at 11:34 AM Saravana Kannan
>>> <> wrote: I took a closer look. So two
>>> different drivers [1] [2] are saying they know how to handle
>>> "arm,vexpress-sysreg" and are expecting to run at the same
>>> time. That seems a bit unusual to me. I wonder if this is a
>>> violation of the device-driver model because this expectation
>>> would never be allowed if these device drivers were actual
>>> drivers registered with driver-core. But that's a discussion
>>> for another time.
>>> To fix this issue you are facing, this patch should work:
> Sorry, that's not a fix. That's a crude hack.
> If device nodes are being handled by drivers without binding a
> driver to struct devices, then not setting OF_POPULATED is wrong.
> So the original patch sets it. There are also very valid reasons
> for allowing OF_POPULATED to be cleared by a driver as discussed
> here [1].
> The approach of the original patch (setting the flag and letting
> the driver sometimes clear it) is also followed by many other
> frameworks like irq, clk, i2c, etc. Even ingenic-timer.c already
> does it for the exact same reason.
> So, why is the vexpress fix a crude hack?
>> As this is also causing trouble on tegra30-cardhu-a04 the only
>> sane solution is to revert it and start over with a proper
>> solution for the vexpress problem and a root cause analysis for
>> the tegra.
> If someone can tell me which of the timer drivers are relevant for
> tegra30-cardhu-a04, I can help fix it. If you want to revert the
> original patch first before waiting for a tegra fix, that's okay by
> me.

It seems the OF_POPULATED flag change spotted something wrong in
different drivers and that is a good thing. Thanks for your patch for

Without putting in question your analysis, we need to stabilize the
release, can you send a revert of your patch?

Let's try to figure out what is happening and fix the issues in the
other drivers for the next cycle.


-- Daniel

<> │ Open source software for ARM SoCs

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