Hi Mark,
On Fri, Nov 27, 2015 at 2:24 PM, Mark Brown <[email protected]> wrote:
> On Fri, Nov 27, 2015 at 02:06:41PM +0100, Geert Uytterhoeven wrote:
>> (replaying to an old mail, as I'm seeing the exact same behavior with current
>> overlay code)
>
> I don't seem to have this mail... I'm not even sure that mailing list
> archive does (at least
>
> http://thread.gmane.org/gmane.linux.kernel.spi.devel/18597
>
> anyway).
It was sent to the devicetree mailing list only, without anyone else CCed.
Probably that's why no one noticed or replied to it before...
>> When adding an SPI master device node to DT, or changing its status to
>> "okay",
>> of_register_spi_devices() will scan for SPI slaves, and will add all of them.
>> Later, the notifier kicks:
>
>> static int of_spi_notify(struct notifier_block *nb, unsigned long action,
>> void *arg)
>> {
>> ...
>>
>> case OF_RECONFIG_CHANGE_ADD:
>> master = of_find_spi_master_by_node(rd->dn->parent);
>> if (master == NULL)
>> return NOTIFY_OK; /* not for us */
>>
>> spi = of_register_spi_device(master, rd->dn);
>
>> Woops, this fails, as the device has been added before!
>> Should the code just check for the existence of the SPI slave first, or would
>> that cause problems when just modifying an existing SPI slave node in DT?
>
> Looking at the I2C code it seems like it's using
> of_node_test_and_set_flag() to check for OF_POPULATED before
> instantiating, doing that manually in every place where it might
> instantiate a device and manually clearing when deinstantiating.
Thanks for looking into that!
> I have to say I don't entirely understand the logic behind how this
> stuff is supposed to work, it's confusing to me why we have separate
> dynamic and static instantiation paths in the first place or why this is
> open coded in the buses. It seems like a more robust thing here is to
> always use the dynamic path even on static instantiation, or to move it
> more into the driver core.
Indeed.
> Ideally I'd like to see the I2C code factored out into the DT core but
> otherwise probably we have to cut'n'paste it.
I'll give that a try...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
