* Tony Lindgren <tony@xxxxxxxxxxx> [140417 09:34]: > * Nishanth Menon <nm@xxxxxx> [140325 08:05]: > > On 03/21/2014 12:20 AM, Lokesh Vutla wrote: > > > From: Dave Gerlach <d-gerlach@xxxxxx> > > > > > > Do not reset GPIO5 at boot-up because GPIO5_7 is used > > > on AM437x GP-EVM to control VTT regulators on DDR3. > > > Without this some GP-EVM boards will fail to boot because > > > of DDR3 corruption. > > How funny :) > > Ideally we would be able to specify which GPIO pins should > maintain their state during the boot. > > AFAIK, this patch currently means that the kernel has no idea > what state the whole GPIO bank is in. At minimum we should > parse the GPIO bank state so the kernel knows it and then it > should be safe to set the no reset flag. > > So for the workaround, can you guys please try to see test > if the old mux trick in the bootloader works to mux the pin > into something PIN_INPUT_PULLUP | MUX_MODE7? Or a PULLDOWN > depending on the direction naturally. That would allow > leaving out the GPIO completely from this. OK so no safe mode as MUX_MODE7 on am335x. So based on the tests done by Dave on various GPIO banks without the reset, this seems OK to do. So applying into omap-for-v3.15/fixes-v2 to get the board booting properly. Naturally this is not a reason to stop further work on making sure the GPIO driver actually knows what state the bank is as suggested by Felipe. Tony -- 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
