u-boot/drivers/pinctrl/uniphier
Masahiro Yamada fdd15b6a86 pinctrl: uniphier: set input-enable before pin-muxing
While IECTRL is disabled, input signals are pulled-down internally.
If pin-muxing is set up first, glitch signals (Low to High transition)
might be input to hardware blocks.

Bad case scenario:
[1] The hardware block is already running before pinctrl is handled.
   (the reset is de-asserted by default or by a firmware, for example)
[2] The pin-muxing is set up.  The input signals to hardware block
   are pulled-down by the chip-internal biasing.
[3] The pins are input-enabled.  The signals from the board reach the
    hardware block.

Actually, one invalid character is input to the UART blocks for such
SoCs as PH1-LD4, PH1-sLD8, where UART devices start to run at the
power on reset.

To avoid such problems, pins should be input-enabled before muxing.

[ ported from Linux commit bac7f4c1bf5e7c6ccd5bb71edc015b26c77f7460 ]

Fixes: 5dc626f836 ("pinctrl: uniphier: add UniPhier pinctrl core support")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2016-03-09 01:10:52 +09:00
..
Kconfig ARM: uniphier: rename CONFIG_MACH_* to CONFIG_ARCH_UNIPHIER_* 2015-09-25 00:27:53 +09:00
Makefile Various Makefiles: Add SPDX-License-Identifier tags 2015-11-10 09:19:52 -05:00
pinctrl-ph1-ld4.c pinctrl: uniphier: add UniPhier PH1-LD4 pinctrl driver 2015-09-25 00:21:13 +09:00
pinctrl-ph1-ld6b.c pinctrl: uniphier: add UniPhier PH1-LD6b pinctrl driver 2015-09-25 00:27:47 +09:00
pinctrl-ph1-pro4.c pinctrl: uniphier: add UniPhier PH1-Pro4 pinctrl driver 2015-09-25 00:23:15 +09:00
pinctrl-ph1-pro5.c pinctrl: uniphier: add UniPhier PH1-Pro5 pinctrl driver 2015-09-25 00:25:29 +09:00
pinctrl-ph1-sld8.c pinctrl: uniphier: add UniPhier PH1-sLD8 pinctrl driver 2015-09-25 00:24:30 +09:00
pinctrl-proxstream2.c pinctrl: uniphier: add UniPhier ProXstream2 pinctrl driver 2015-09-25 00:26:27 +09:00
pinctrl-uniphier-core.c pinctrl: uniphier: set input-enable before pin-muxing 2016-03-09 01:10:52 +09:00
pinctrl-uniphier.h bug.h: move BUILD_BUG_* defines to include/linux/bug.h 2016-01-25 10:39:59 -05:00