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authorLokesh Vutla <lokeshvutla@ti.com>2013-04-17 20:49:40 +0000
committerTom Rini <trini@ti.com>2013-05-10 08:25:55 -0400
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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>
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@@ -3323,6 +3323,10 @@ Configuration Settings:
offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
directly. You should not need to touch this setting.
+- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
+ This is set by OMAP boards for the max time that reset should
+ be asserted. See doc/README.omap-reset-time for details on how
+ the value can be calulated on a given board.
The following definitions that deal with the placement and management
of environment data (variable area); in general, we support the