[PATCH] Add lvgl_hello: Sample Hello world app using littleVGL and libbsd

[Vijay Kumar Banerjee]

On Wed, Sep 18, 2019 at 12:54 AM Christian Mauderer <list at c-mauderer.de>
wrote:

>
> > Hi,
> > I followed the error and figured out that the reason for the error was a
> > call to
> > `rtems_task_wake_after` which was coming from the `udelay()` call in
> bbb-i2c
> > in function `am335x_i2c_reset`. For now, commenting out the udelay calls
> > work
> > without error and I can also see the lvgl example working.
> >
> > What is the use of udelay there? Can it be removed? if not, what's the
> > better way
> > to make a delay at system initialization than `rtems_task_wake_after`?
>
> I agree that it is quite likely that udelay doesn't work correctly when
> the system isn't booted yet. Most likely that's the reason for the error.
>
> I'm not entirely sure whether the udelay has been there before I updated
> the driver or whether I took it over from the FreeBSD driver. But it's
> not really relevant. Most likely the times are either required by the
> manual or they had been necessary during some tests.
>
> The am335x_i2c_reset is only called during initialization (in that case
> during am335x_i2c_bus_register). So it shouldn't be a problem to replace
> them with a busy wait. You can use the rtems_counter_delay_nanoseconds()
> for that.
>
>
> This worked. I have posted a patch and started a discussion here:
https://lists.rtems.org/pipermail/devel/2019-September/027748.html
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