Hi John,
On 11/11/2014 18:15, John Tobias wrote:
You add a new entry point here (spl_board_mmc_init), but why cannot you do this in the functions already supplied by SPL ? Why not in board_init_f ?
When the spl_mmc_load_image function being called, it call mmc_initialize. By default, the mmc_initialize call board_mmc_init. By looking the said function, it initialize all mmc ports.
While, in spl_board_mmc_init, only initialize the current mmc port.
ok - but which is the issue by initializing all ports ? I mean, if board_mmc_init initialize all ports including what you need in SPL, which is the reason to exclude the other ones ?
When board_mmc_init initialize all ports, we can issue a command at uboot console to switch to different port. e.g:
mmc dev 0 (e.g. SD4) mmc dev 1 (e.g. SD2) mmc dev 2 (e.g. SD3)
We can also re-map which is index 0, 1 and 2 by re-arranging the contents of
struct fsl_esdhc_cfg usdhc_cfg[3] = { {USDHC4_BASE_ADDR}, {USDHC2_BASE_ADDR}, {USDHC3_BASE_ADDR}, };
Assuming the bootstrap is configured to port 3 (USDHC3). The SPL image will call spl_mmc_load_image to load the uboot image. In order to do that, it will call the find_mmc_device(0), based on example above the index 0 is port 4, index 1 is port 2 and index 2 is port 3. The find_mmc_device will return with errors because it couldn't initialize the said port.
So by default, the user should switch back the bootstrap to port 4 in order to load the uboot correctly. Then, if the user really want to use the different ports, they have to change the arrangement of the contents of usdhc_cfg and compile the u-boot again.
In spl_board_mmc_init function, it will read the bootstrap and configure it. The settings are passed to fsl_esdhc_initialize which is to be stored in index 0. So, find_mmc_device(0) could get a correct information.
Then, switching to different bootstrap doesn't require to re-compile the image.
This is not enough for adding a new exported weak function, that reamins undocumented, and does not avoid using #ifdef, only moved into drivers/mmc/mmc.c.
We have other cases where the behavior is different between SPL and U-Boot, and this is handled in board file using the same #ifdef CONFIG_SPL_BUILD.
The question is: why do you need to change the API (as I said, it remains undocumented) instead of doing :
int board_mmc_init(bd_t *bis) {
#ifdef CONFIG_SPL_BUILD <initialization single port based on bootstrap> #else <instantiate all ports as usual> #endif
Best regards, Stefano Babic