Hi Tom, On 22 March 2017 at 08:37, Tom Rini <tr...@konsulko.com> wrote: > On Wed, Mar 22, 2017 at 07:05:38AM -0600, Simon Glass wrote: >> Hi Tom, >> >> On 19 March 2017 at 18:47, Tom Rini <tr...@konsulko.com> wrote: >> > On Sun, Mar 19, 2017 at 12:59:19PM -0600, Simon Glass wrote: >> >> At present we have a lot of ad-hoc init functions related to boards, for >> >> example board_early_init_f(), board_misc_init_f() and dram_init(). >> >> >> >> There are used in different ways by different boards as useful hooks to >> >> do the required init and sequence it correctly. Some functions are always >> >> enabled but have a __weak default. Some are controlled by the existence >> >> of a CONFIG. >> >> >> >> There are two main init sequences: board_init_f() (f for running from >> >> read-only flash) which runs before relocation and board_init_r() (r for >> >> relocated) which runs afterwards. >> >> >> >> One problem with the current sequence is that it has a lot of >> >> arch-specific #ifdefs around various functions. There are also #ifdefs >> >> for various features. There has been quite a bit of discussion about how >> >> to tidy this up and at least one RFC series[1]. >> >> >> >> Now that we have driver model we can use this to deal with the init >> >> sequences. This approach has several advantages: >> >> >> >> - We have a path to remove the #ifdefs >> >> - It is easy for multiple parts of the code to implement the same hook >> >> - We can track what is called and what is not >> >> - We don't need weak functions >> >> - We can eventually adjust the sequence to improve naming or to add new >> >> init phases >> >> - It provides a model for how we might deal with ft_board_setup() and >> >> friends >> >> >> >> This series starts the process of replacing the pre-relocation init >> >> sequence with a driver-model solution. It defines a uclass, adds tests >> >> and converts sandbox and a few x86 boards over to use this new setup. >> >> >> >> This series is not ready for use yet as the rest of the init sequence >> >> hooks need to be converted. But there is enough here to show the idea. >> >> >> >> Comments welcome. >> >> >> >> [1] https://lists.denx.de/pipermail/u-boot/2011-August/098718.html >> > >> > How does this look, size wise? With all of these conversions and >> > clean-ups, we really need to be size concious as well as it all keeps >> > adding up. Thanks! >> >> It include size a bit - e.g. x86 808 bytes of text, although that does >> include a few extra features. > > How about if we don't include some of the extra debug/demo type features > (which are useful at times, certainly) ? We keep adding things that add > a few bytes here and a few bytes there and it all adds up.
Yes it's very important that the base version doesn't increase size, or at least only minimally. I should have examined that more closely in the RFC - my intent was really to get comments on the approach, > > [snip] >> I think I can use a linker-list approach to reduce the overhead. But I >> still think the driver has value as it provides a means of adding >> hooks to do board-specific things from drivers, something that we keep >> running into. Also the idea of a board 'driver' seems conceptually >> useful. >> >> So one approach would be to have: >> >> 1. A linker-list-based board hook setup, where you can declare, for example: >> >> static int ivybridge_dram_init(void) >> { >> ... >> } >> U_BOOT_BOARD_HOOK(ivybridge_dram_init, BOARD_F_DRAM_INIT); >> >> This should be pretty cheap, perhaps <200 bytes with some care. >> >> >> 2. An optional BOARD uclass which can be used for more involved >> situations, but with a higher code size penalty. > > OK. But I also recall that we had talked about trying to condense and > re-factor things. My worry about an approach like this is it allows for > us to more easily get back into the bad habits of having each > architecture solve similar problems with different solutions. Yes that's true and I've been pushing back on this for a while. For example there is quite a bit of pressure to add board-specific init code to drivers with driver model. So far I think we have been able to avoid this using device tree and other drivers. For example if MMC needs a clock we can find the required clock by phandle and call the clock driver. So are you thinking we should limit this to just a simple hook approach for now, and then consider the board uclass down the track? Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot