On 04/23/2014 09:59 AM, Tony Lindgren wrote:
* Dave Gerlach <d-gerlach@xxxxxx> [140422 12:53]:
On 04/22/2014 02:01 PM, Tony Lindgren wrote:
* Dave Gerlach <d-gerlach@xxxxxx> [140422 11:52]:
This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
bootloader configures gpio5_7 to control the DDR3 termination regulator,
the linked patch prevents that gpio bank from being reset and losing
the previously configured state, and this patch binds the gpio to a
regulator so the kernel is aware of the state of the gpio.
[1] https://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg102941.html
Setting up the GPIO regulator makes sense to me. But the hack in the
link above is potentially a nasty time bomb for anybody trying to
use GPIO bank 5 on that board.
What tests have been done that the GPIO bank behaves properly when
it's not reset?
We've been using this configuration on this board for a while without any
apparent issues. Also, am335x-evmsk already uses the same idea for the VTT
regulator on board from commit 6046adb6ad701026c10adeac8d6a4138895f12e5
[ARM: dts: am335x-evmsk: Do not reset gpio0] and I am unaware of any issues
with that either.
OK. Do you have other GPIOs in use as interrupts for devices in these
banks and do they work fine?
I dont see any interrupts in use from gpio5 bank but as a quick test if
I add ti,no-reset-on-init to gpio3 and gpio4 I see no issue with
matrix-keypad operation which uses gpios from each of those banks.
Also, can you please test to make sure this works with the most recent
Javier's GPIO patches that had the issue of not booting on am335x-evmsk?
Yes, when using Javier's patches in addition to this patch [1], which
was found to be necessary through this discussion [2], the AM437x GP EVM
boots fine with linux-next with my regulator patch and gpio5 no reset
patch applied.
Regards,
Dave
[1] https://patchwork.kernel.org/patch/4041881/
[2] http://marc.info/?t=139817273800014&r=1&w=2
Regards,
Tony
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