After enabling a module, SW has to wait on IDLEST bit until it is Fully functional. This wait is missing for UART module and there is a immediate access of UART registers after this. So there is a chance of hang on this module( This can happen when we are running from MPU SRAM). So waiting for IDLEST bit.
Signed-off-by: Lokesh Vutla lokeshvutla@ti.com --- arch/arm/cpu/armv7/am33xx/clock_am43xx.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/arch/arm/cpu/armv7/am33xx/clock_am43xx.c b/arch/arm/cpu/armv7/am33xx/clock_am43xx.c index d0bc234..31188c8 100644 --- a/arch/arm/cpu/armv7/am33xx/clock_am43xx.c +++ b/arch/arm/cpu/armv7/am33xx/clock_am43xx.c @@ -53,6 +53,8 @@ const struct dpll_regs dpll_ddr_regs = {
void setup_clocks_for_console(void) { + u32 clkctrl, idlest = MODULE_CLKCTRL_IDLEST_DISABLED; + /* Do not add any spl_debug prints in this function */ clrsetbits_le32(&cmwkup->wkclkstctrl, CD_CLKCTRL_CLKTRCTRL_MASK, CD_CLKCTRL_CLKTRCTRL_SW_WKUP << @@ -63,6 +65,13 @@ void setup_clocks_for_console(void) MODULE_CLKCTRL_MODULEMODE_MASK, MODULE_CLKCTRL_MODULEMODE_SW_EXPLICIT_EN << MODULE_CLKCTRL_MODULEMODE_SHIFT); + + while ((idlest == MODULE_CLKCTRL_IDLEST_DISABLED) || + (idlest == MODULE_CLKCTRL_IDLEST_TRANSITIONING)) { + clkctrl = readl(&cmwkup->wkup_uart0ctrl); + idlest = (clkctrl & MODULE_CLKCTRL_IDLEST_MASK) >> + MODULE_CLKCTRL_IDLEST_SHIFT; + } }
void enable_basic_clocks(void)