On Mon, Aug 18, 2008 at 03:58:46PM +0200, Laurent Pinchart wrote: [...] > > Not exactly. But you can do this way, if you need to preserve > > a direction. What I did is a bit different though. > > > > qe_gpio_set_dedicated() actually just restores a mode that > > firmware had set up, including direction (since direction could > > be a part of dedicated configuration). > > > > That is, upon GPIO controller registration, we save all registers, > > then driver can set up a pin to a GPIO mode via standard API, and > > then it can _revert_ a pin to a dedicated function via > > qe_gpio_set_dedicated() call. Dedicated function is specified by > > the firmware (or board file), we're just restoring it. > > The semantic of the set_dedicated() operation needs to be clearly > defined then.
It is. We set up a dedicated function that firmware (or board file) has configured. > I can live with this behaviour, but it might not be > acceptable for everybody. For example? > Your patch requires the firmware to set a pin in dedicated mode at > bootup in order to be used later in dedicated mode. Yes. On a PowerPC this is always true: firmware should set up PIO config. Linux' board file could fixup the firmware though. Another option would be to add some argument to the set_dedicated call, thus the software could specify arbitrary dedicated function (thus no need to save/restore anything). But this would be SOC-model specific, thus no driver can use this argument anyway. > If, for some > reason (driver not loaded, ...), no GPIO user shows up for that > pin, it will stay configured in dedicated mode. Yes. > It might be better to set the PAR bit unconditionally in Why it might be better? That way you may set up wrong _GPIO_ mode, because you didn't set PAR bit (when PAR bit set DIR/ODR/DAT bits are losing their meanings). > qe_gpio_set_dedicated() instead of restoring its value. That way > the board initialization code could just set the DIR, DAT and ODR > bits for dedicated mode but still configure the pin in GPIO mode. -- Anton Vorontsov email: [EMAIL PROTECTED] irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
