ARM: OMAP5: Fix warm reset with USB cable connected
authorLokesh Vutla <lokeshvutla@ti.com>
Wed, 17 Apr 2013 20:49:40 +0000 (20:49 +0000)
committerTom Rini <trini@ti.com>
Fri, 10 May 2013 12:25:55 +0000 (08:25 -0400)
commit0b1b60c77954df19b5a601e2ba87614f2d0bbb8b
tree3dff44e2598611673743d56bd3480d9acf97b3f5
parent15191c91a240bd8683ca40e6c4b8b8c44b98412f
ARM: OMAP5: Fix warm reset with USB cable connected

Warm reset on OMAP5 freezes when USB cable is connected.
Fix requires PRM_RSTTIME.RSTTIME1 to be programmed
with the time for which reset should be held low for the
voltages and the oscillator to reach stable state.

There are 3 parameters to be considered for calculating
the time, which are mostly board and PMIC dependent.
-1- Time taken by the Oscillator to shut + restart
-2- PMIC OTP times
-3- Voltage rail ramp times, which inturn depends on the
PMIC slew rate and value of the voltage ramp needed.

In order to keep the code in u-boot simple, have a way
for boards to specify a pre computed time directly using
the 'CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC'
option. If boards fail to specify the time, use a default
as specified by 'CONFIG_DEFAULT_OMAP_RESET_TIME_MAX_USEC' instead.
Using the default value translates into some ~22ms and should work in
all cases.
However in order to avoid this large delay hiding other bugs,
its recommended that all boards look at their respective data
sheets and specify a pre computed and optimal value using
'CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC'

In order to help future board additions to compute this
config option value, add a README at doc/README.omap-reset-time
which explains how to compute the value. Also update the toplevel
README with the additional option and pointers to
doc/README.omap-reset-time.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
[rnayak@ti.com: Updated changelog and added the README]
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
README
arch/arm/cpu/armv7/omap-common/clocks-common.c
arch/arm/cpu/armv7/omap-common/reset.c
arch/arm/cpu/armv7/omap5/hwinit.c
arch/arm/cpu/armv7/omap5/prcm-regs.c
arch/arm/include/asm/arch-omap4/sys_proto.h
arch/arm/include/asm/arch-omap5/clocks.h
arch/arm/include/asm/arch-omap5/sys_proto.h
arch/arm/include/asm/omap_common.h
doc/README.omap-reset-time [new file with mode: 0644]
include/configs/omap5_uevm.h