Section 4.1.2 of Freescale Application Note AN4199 describes the configuration required to operate the mx28 from a 5V source without a battery.
This patch changes the behaviour of the dropout control of the DC-DC converter (refer to section 11.12.9 of the mx28 Application Processor Reference Manual - Document Number: MCIMX28RM, Rev 2, 08/2013) to the following: - Always use 4P2 Linear Regulator if CONFIG_SYS_MXS_VDD5V_ONLY is defined - Switch between 4P2 Linear Regulator and Battery, using whichever has the highest voltage if CONFIG_SYS_MXS_VDD5V_ONLY isnot set (this is the same as the pre-patch behaviour)
Signed-off-by: Graeme Russ gruss@tss-engineering.com Signed-off-by: Damien Gotfroi dgotfroi@greenwatch.be ---
Changes in v2 - Implemented Damien Gotfroi's simplified version
Changes in v3 - Updated commit message - Explicitly use POWER_DCDC4P2_DROPOUT_CTRL_SRC_4P2 for the DCDC4P2_DROPOUT_CONFIG define (it is 0x0 so it make no functional difference)
--- arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c index 7fb734e..c342217 100644 --- a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c +++ b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c @@ -14,6 +14,13 @@
#include "mxs_init.h"
+#ifdef CONFIG_SYS_MXS_VDD5V_ONLY +#define DCDC4P2_DROPOUT_CONFIG POWER_DCDC4P2_DROPOUT_CTRL_100MV | \ + POWER_DCDC4P2_DROPOUT_CTRL_SRC_4P2 +#else +#define DCDC4P2_DROPOUT_CONFIG POWER_DCDC4P2_DROPOUT_CTRL_100MV | \ + POWER_DCDC4P2_DROPOUT_CTRL_SRC_SEL +#endif /** * mxs_power_clock2xtal() - Switch CPU core clock source to 24MHz XTAL * @@ -303,8 +310,7 @@ static void mxs_power_init_4p2_params(void)
clrsetbits_le32(&power_regs->hw_power_dcdc4p2, POWER_DCDC4P2_DROPOUT_CTRL_MASK, - POWER_DCDC4P2_DROPOUT_CTRL_100MV | - POWER_DCDC4P2_DROPOUT_CTRL_SRC_SEL); + DCDC4P2_DROPOUT_CONFIG);
clrsetbits_le32(&power_regs->hw_power_5vctrl, POWER_5VCTRL_CHARGE_4P2_ILIMIT_MASK,