From 4850ab9a4f441129b1cde021d58855b3936c4e51 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Fri, 6 Jan 2012 12:14:40 +0000 Subject: [PATCH] tegra2: Fix conflicting pinmux for UARTA Tegra appears to boot with function UARTA pre-selected on mux group SDB. If two mux groups are both set to the same function, it's unclear which group's pins drive the RX signals into the HW module. For UARTA, SDB certainly overrides group IRTX in practice. To solve this, configure some alternative function on SDB to avoid the conflict. Also, tri-state the group to avoid driving any signal onto it until we know what's connected. Signed-off-by: Stephen Warren Acked-by: Simon Glass Tested-by: Simon Glass Signed-off-by: Tom Warren --- arch/arm/cpu/armv7/tegra2/funcmux.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm/cpu/armv7/tegra2/funcmux.c b/arch/arm/cpu/armv7/tegra2/funcmux.c index 0878f51110..140f8a7370 100644 --- a/arch/arm/cpu/armv7/tegra2/funcmux.c +++ b/arch/arm/cpu/armv7/tegra2/funcmux.c @@ -37,6 +37,18 @@ int funcmux_select(enum periph_id id, int config) pinmux_set_func(PINGRP_IRTX, PMUX_FUNC_UARTA); pinmux_tristate_disable(PINGRP_IRRX); pinmux_tristate_disable(PINGRP_IRTX); + /* + * Tegra appears to boot with function UARTA pre-selected on + * mux group SDB. If two mux groups are both set to the same + * function, it's unclear which group's pins drive the RX + * signals into the HW module. For UARTA, SDB certainly + * overrides group IRTX in practice. To solve this, configure + * some alternative function on SDB to avoid the conflict. Also, + * tri-state the group to avoid driving any signal onto it until + * we know what's connected. + */ + pinmux_tristate_enable(PINGRP_SDB); + pinmux_set_func(PINGRP_SDB, PMUX_FUNC_SDIO3); break; case PERIPH_ID_UART2: -- 2.39.5