On Wed, Mar 22, 2017 at 08:43:54AM -0600, Simon Glass wrote: > 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?
Looking over init_sequence_[rf], I can certainly see the case for "ug, this is ugly and we need to make it better" (and I now wonder if we don't have a lot more places where we need INIT_FUNC_WATCHDOG_RESET, anyhow...). But for the moment we seem to be able to resist adding more calls here. And I would like to see if we can rework / reduce the current table before we try and simplify and clean-up the mechanism that we use to handle them. -- Tom
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