| David Jander | 9db1bfa | 2011-07-13 21:11:53 +0000 | [diff] [blame] | 1 | U-Boot for Freescale i.MX5x |
| 2 | |
| 3 | This file contains information for the port of U-Boot to the Freescale |
| 4 | i.MX5x SoCs. |
| 5 | |
| 6 | 1. CONFIGURATION OPTIONS/SETTINGS |
| 7 | --------------------------------- |
| 8 | |
| 9 | 1.1 CONFIG_MX51_PLL_ERRATA: Workaround for i.MX51 PLL errata. |
| 10 | This option should be enabled by all boards using the i.MX51 silicon |
| 11 | version up until (including) 3.0 running at 800MHz. |
| 12 | The PLL's in the i.MX51 processor can go out of lock due to a metastable |
| 13 | condition in an analog flip-flop when used at high frequencies. |
| 14 | This workaround implements an undocumented feature in the PLL (dither |
| 15 | mode), which causes the effect of this failure to be much lower (in terms |
| 16 | of frequency deviation), avoiding system failure, or at least decreasing |
| 17 | the likelihood of system failure. |
| Benoît Thébaudeau | 39e8576 | 2012-11-05 10:07:04 +0000 | [diff] [blame^] | 18 | |
| 19 | 1.2 CONFIG_SYS_MAIN_PWR_ON: Trigger MAIN_PWR_ON upon startup. |
| 20 | This option should be enabled for boards having a SYS_ON_OFF_CTL signal |
| 21 | connected to GPIO1[23] and triggering the MAIN_PWR_ON signal like in the |
| 22 | reference designs. |