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linux/drivers/pinctrl/uniphier
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Masahiro Yamada bac7f4c1bf 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.

Fixes: 6e90889202 ("pinctrl: UniPhier: add UniPhier pinctrl core support")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reported-by: Dai Okamura <okamura.dai@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-10-27 11:07:49 +01:00
..
Kconfig pinctrl: UniPhier: add UniPhier PH1-LD6b pinctrl driver 2015-07-16 09:40:08 +02:00
Makefile pinctrl: UniPhier: add UniPhier PH1-LD6b pinctrl driver 2015-07-16 09:40:08 +02:00
pinctrl-ph1-ld4.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-ph1-ld6b.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-ph1-pro4.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-ph1-pro5.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-ph1-sld8.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-proxstream2.c pinctrl: uniphier: add SD card pinmux settings 2015-10-02 04:07:15 -07:00
pinctrl-uniphier-core.c pinctrl: uniphier: set input-enable before pin-muxing 2015-10-27 11:07:49 +01:00
pinctrl-uniphier.h pinctrl: UniPhier: add UniPhier pinctrl core support 2015-07-16 09:39:38 +02:00