Re: [PATCH] staging: fbtft: fb_upd161704: replace udelay with usleep_range

[Andy Shevchenko]

On Wed, Sep 16, 2026 at 03:08:06PM +0300, Ömer PALA wrote:
> On Wed, Sep 16, 2026 at 12:39:28PM +0300, Andy Shevchenko wrote:

...

> Second, do you understand the difference on what
> code is doing before and after your change?
> I understand that udelay() provides deterministic, busy-wait timing required for
> hardware register initialization, whereas usleep_range() introduces scheduler
> overhead and non-deterministic delays.
> Out of technical curiosity regarding the driver IC: theoretically, if we knew
> the exact window between the hardware lock/stabilization
> time (min) and the internal state-machine timeout (max) from the datasheet,
> would a range like usleep_range(min, max) be acceptable,
> or does scheduler wake-up latency make it too risky for
> timing-critical init sequences without hardware validation?
> I will drop this patch series.

It's not only about timings, longer sleeps most likely are fine, the main
problem is atomicity.

...

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-- 
With Best Regards,
Andy Shevchenko