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| author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2015-10-20 17:25:09 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-12-09 14:34:32 -0500 |
| commit | 717991ddefe125a0f68f10b44bd7178e2208fdfd (patch) | |
| tree | 3c3e474a24c3b28369a76c47181cbdc6d400574f | |
| parent | ea9130ac6927fc4fe26cab6aa25d9e4172c38cd5 (diff) | |
| download | lwn-717991ddefe125a0f68f10b44bd7178e2208fdfd.tar.gz lwn-717991ddefe125a0f68f10b44bd7178e2208fdfd.zip | |
pinctrl: uniphier: set input-enable before pin-muxing
commit bac7f4c1bf5e7c6ccd5bb71edc015b26c77f7460 upstream.
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: 6e9088920258 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/pinctrl/uniphier/pinctrl-uniphier-core.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c b/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c index 918f3b643f1b..589872cc8adb 100644 --- a/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c +++ b/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c @@ -539,6 +539,12 @@ static int uniphier_pmx_set_one_mux(struct pinctrl_dev *pctldev, unsigned pin, unsigned reg, reg_end, shift, mask; int ret; + /* some pins need input-enabling */ + ret = uniphier_conf_pin_input_enable(pctldev, + &pctldev->desc->pins[pin], 1); + if (ret) + return ret; + reg = UNIPHIER_PINCTRL_PINMUX_BASE + pin * mux_bits / 32 * reg_stride; reg_end = reg + reg_stride; shift = pin * mux_bits % 32; @@ -563,9 +569,7 @@ static int uniphier_pmx_set_one_mux(struct pinctrl_dev *pctldev, unsigned pin, return ret; } - /* some pins need input-enabling */ - return uniphier_conf_pin_input_enable(pctldev, - &pctldev->desc->pins[pin], 1); + return 0; } static int uniphier_pmx_set_mux(struct pinctrl_dev *pctldev, |