On 05/06/2014 11:18 AM, Tim Harvey wrote:
On Mon, Apr 28, 2014 at 1:17 PM, Tim Harvey tharvey@gateworks.com wrote:
Switch to an SPL image. The SPL for Ventana does the following:
- setup i2c and read the factory programmed EEPROM to obtain DRAM config and model for board-specific calibration data
- configure DRAM per CPU/size/layout/devices/calibration
- load u-boot.img from NAND or MTD depending on boot device and jump to it
This allows for a single SPL+u-boot.img to replace the previous multiple board configurations.
<snip> > + > +static void i2c_setup_iomux(void) > +{ > + if (is_cpu_type(MXC_CPU_MX6Q)) > + setup_i2c(0, CONFIG_SYS_I2C_SPEED, 0x7f, &mx6q_i2c_pad_info0); > + else > + setup_i2c(0, CONFIG_SYS_I2C_SPEED, 0x7f, &mx6dl_i2c_pad_info0); > +} > + <snip> > + > +/* > + * called from C runtime startup code (arch/arm/lib/crt0.S:_main) > + * - we have a stack and a place to store GD, both in SRAM > + * - no variable global data is available > + */ > +void board_init_f(ulong dummy) > +{ > + struct ventana_board_info ventana_info; > + int board_model; > + > + /* iomux and setup of i2c */ > + i2c_setup_iomux(); > + timer_init(); > + board_model = read_eeprom(I2C_GSC, &ventana_info); > + > + /* provide some some default: 32bit 128MB */ > + if (GW_UNKNOWN == board_model) { > + ventana_info.sdram_width = 2; > + ventana_info.sdram_size = 3; > + } > + spl_dram_init(8 << ventana_info.sdram_width, > + 16 << ventana_info.sdram_size, > + board_model); > + > + arch_cpu_init(); > + > + /* Clear the BSS. */ > + memset(__bss_start, 0, __bss_end - __bss_start); > + > + /* Set global data pointer. */ > + gd = &gdata; > + > + board_early_init_f(); > + > + preloader_console_init(); > + > + board_init_r(NULL, 0); > +}
Stefano / York,
While preparing for a v3 patch series of my IMX6 SPL bootloader, I find that commit dec1861be90c948ea9fb771927d3d26a994d2e20 [1] breaks the above code because gd is now needed within setup_i2c.
I've always been a bit fuzzy on the order of the above calls so I dug through the code and I think I understand things better. Please correct any wrong assumptions I'm making below:
- assignment to gd should 'always' be first (before anything needs
it, so why not do it first)
- arch_cpu_init() should go next as this sets up very low level
CPU/SoC resources (in this case AIPS config and watchdog disable)
- board_early_init_f() should be next as that sets up any board-specific iomux
- any additional iomux necessary for SPL should go next (I take care
of i2c iomux and setup here)
- timer_init() next as you need a timer for UART and mxc i2c (for
delays and busy checks)
- preloader_console_init() next as we are now able to send something
over the UART (this gives me early debug for sdram config now too!)
- sdram setup goes next
- after sdram is setup, the bss can be cleared
- board_init_r - pass over to generic SPL code which will load/call
an image based on boot device
So, if the above is correct, I should rework the above function as follows:
void board_init_f(ulong dummy) { struct ventana_board_info ventana_info; int board_model;
/* Set global data pointer. */ gd = &gdata; /* setup AIPS and disable watchdog */ arch_cpu_init(); /* iomux and setup of i2c */ board_early_init_f(); i2c_setup_iomux(); /* setup GP timer */ timer_init(); /* UART clocks enabled and gd valid - init serial console */ preloader_console_init(); /* read/validate EEPROM info to determine board model and SDRAM cfg */ board_model = read_eeprom(I2C_GSC, &ventana_info); /* provide some some default: 32bit 128MB */ if (GW_UNKNOWN == board_model) { ventana_info.sdram_width = 2; ventana_info.sdram_size = 3; } /* configure MMDC for SDRAM width/size and per-model calibration */ spl_dram_init(8 << ventana_info.sdram_width, 16 << ventana_info.sdram_size, board_model); /* Clear the BSS. */ memset(__bss_start, 0, __bss_end - __bss_start); /* load/boot image from boot device */ board_init_r(NULL, 0);}
Does this make sense?
Tim,
I agree gd should be set first if the memory is available. My previous change to this i2c driver was to make sure it works without DRAM. Since it uses a data structure, it has no other place to go.
York