| Jean-Christophe PLAGNIOL-VILLARD | 75fe391 | 2008-09-30 20:08:36 +0200 | [diff] [blame] | 1 | U-Boot for Freescale i.MX31 |
| 2 | |
| 3 | This file contains information for the port of U-Boot to the Freescale |
| 4 | i.MX31 SoC. |
| 5 | |
| 6 | 1. CONFIGURATION OPTIONS/SETTINGS |
| 7 | --------------------------------- |
| 8 | |
| 9 | 1.1 Configuration of MC13783 SPI bus |
| 10 | ------------------------------------ |
| 11 | The power management companion chip MC13783 is connected to the |
| 12 | i.MX31 via an SPI bus. Use the following configuration options |
| 13 | to setup the bus and chip select used for a particular board. |
| 14 | |
| 15 | CONFIG_MC13783_SPI_BUS -- defines the SPI bus the MC13783 is connected to. |
| 16 | Note that 0 is CSPI1, 1 is CSPI2 and 2 is CSPI3. |
| 17 | CONFIG_MC13783_SPI_CS -- define the chip select the MC13783 s connected to. |
| 18 | |
| 19 | 1.2 Timer precision |
| 20 | ------------------- |
| 21 | CONFIG_MX31_TIMER_HIGH_PRECISION |
| 22 | |
| 23 | Enable higher precision timer. The low-precision timer |
| 24 | (default) provides approximately 4% error, whereas the |
| 25 | high-precision timer is about 0.4% accurate. The extra |
| 26 | accuracy is achieved at the cost of higher computational |
| 27 | overhead, which, in places where time is measured, should |
| 28 | not be critical, so, it should be safe to enable this |
| 29 | option. |