Re: [PATCH tty 1/1] serial: 8250: Change console_msr_work to IRQ_WORK_LAZY

[Andy Shevchenko]

On Fri, Aug 28, 2026 at 06:06:50PM +0100, Jon Hunter wrote:
> On 28/08/2026 17:06, Sebastian Andrzej Siewior wrote:
> > On 2026-08-28 18:04:08 [+0206], John Ogness wrote:
> > > For some platforms it is a problem to queue irq_work when entering
> > > cpuidle states. Since irq_work is used for deferred MSR handling,
> > > any atomic console printing when entering cpuidle states can lead
> > > to the affected hardware hanging. Tegra20 and Tegra30 are examples
> > > of such platforms. Avoiding raising the irq_work IRQ has shown to
> > > circumvent the problem.
> > 
> > I would argue that this is done for the benefit of less interrupts since
> > there no need to handle console_msr_work immediately. With the side
> > effect that it might fix a bug that was not yet reported on Tegra[23]0.
> > 
> > Ideally the Tegra folks should figure out what exactly is broken instead
> > of adding duct tape everywhere else.
> 
> Yes that would be ideal. Unfortunately these are old devices now and very
> much in maintenance mode so getting to the bottom of this now is unlikely.
> You may say then why don't we completely deprecate these, but then you
> could argue the other way and say they have been working fine up until
> now.

This is a trade-off between burden of supporting them vs. developing and move
on on more important things. Personally I consider non-blocking console feature
is *much* more important than a few "working fine up until now" outdated
platforms (side example, recently the whole i486 support was ripped off, while
working fine...).

-- 
With Best Regards,
Andy Shevchenko