| Message ID | 1445329509-6252-1-git-send-email-yamada.masahiro@socionext.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Oct 20, 2015 at 10:25 AM, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > 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> > --- > > Hi Linus, > > If it is not too late, please apply this fix for Linux 4.3. It's too late at this point. Patch is applied for devel and will come into v4.4 and from there to -stable. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c b/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c index 918f3b6..589872c 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,
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> --- Hi Linus, If it is not too late, please apply this fix for Linux 4.3. Thanks, Masahiro drivers/pinctrl/uniphier/pinctrl-uniphier-core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)