| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.3 082/125] pinctrl: uniphier: set input-enable before pin-muxing | Date | Mon, 7 Dec 2015 10:01:35 -0500 |
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4.3-stable review patch. If anyone has any objections, please let me know.
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From: Masahiro Yamada <yamada.masahiro@socionext.com>
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>
--- drivers/pinctrl/uniphier/pinctrl-uniphier-core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- 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(stru 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(stru 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,
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