Hi Mark, On Fri, Nov 27, 2015 at 2:24 PM, Mark Brown <broonie@xxxxxxxxxx> 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 -- geert@xxxxxxxxxxxxxx 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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
