On Thu, Dec 11, 2014 at 11:36 AM, Rafał Miłecki <zajec5@xxxxxxxxx> wrote: > On 9 December 2014 at 10:12, Maxime Ripard > <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote: >> On Mon, Dec 08, 2014 at 05:59:11PM +0100, Geert Uytterhoeven wrote: >>> > I think that implementing support for this extra SPI layer will >>> > actually require more code/tricks than a separated driver. >>> >>> Yes, it will require more code, as spi-gpio is more generic than your simple >>> implementation. But the end result is more flexible and reusable. >>> >>> The only thing missing is the programmable OE and reset pins, >>> which are assumed hardwired by the gpio-74x164 driver. >>> These could be implemented using new gpio-oe and gpio-reset >>> properties. >> >> From my (very) vague memories of it, OE was actually supported by >> using it as spi-gpio's chip select. >> >> So I'd say that only the gpio-reset should be implemented. > > I've tracked how spi_bitbang_transfer_one does work. Long story short it does: [deleted standard SPI protocol] > As you can see, we don't call OE in spi_gpio_chipselect. So currently > both input signals and unhandled: OE and SRCLR. Luckily for me, it > appears my bootloader puts them in a wanted state, but this still > should be handled somehow. I think you can just add two properties (one array for OE, one for SRCLR) to the bindings for the gpio-74x164 driver, so it can set those GPIO pins, if present. Note that they should be arrays, as gpio-74x164 supports\ daisy-chaining chips. 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