2016-03-04 15:56 GMT+09:00 Masahiro Yamada <yamada.masah...@socionext.com>: > 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. > > [ ported from Linux commit bac7f4c1bf5e7c6ccd5bb71edc015b26c77f7460 ] > > Fixes: 5dc626f83619 ("pinctrl: uniphier: add UniPhier pinctrl core support") > Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
Applied to u-boot-uniphier/master. -- Best Regards Masahiro Yamada _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot