On Fri, Jan 6, 2012 at 2:14 PM, Stephen Warren swarren@nvidia.com wrote:
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 swarren@nvidia.com
Tested on Seaboard.
Acked-by: Simon Glass sjg@chromium.org Tested-by: Simon Glass sjg@chromium.org
arch/arm/cpu/armv7/tegra2/funcmux.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/arch/arm/cpu/armv7/tegra2/funcmux.c b/arch/arm/cpu/armv7/tegra2/funcmux.c index 0878f51..140f8a7 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:
1.7.0.4