This is a note to let you know that I've just added the patch titled pinctrl: uniphier: set input-enable before pin-muxing to the 4.3-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: pinctrl-uniphier-set-input-enable-before-pin-muxing.patch and it can be found in the queue-4.3 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From bac7f4c1bf5e7c6ccd5bb71edc015b26c77f7460 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Date: Tue, 20 Oct 2015 17:25:09 +0900 Subject: pinctrl: uniphier: set input-enable before pin-muxing From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Reported-by: Dai Okamura <okamura.dai@xxxxxxxxxxxxx> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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, Patches currently in stable-queue which might be from yamada.masahiro@xxxxxxxxxxxxx are queue-4.3/pinctrl-uniphier-set-input-enable-before-pin-muxing.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html