ARM: OMAP2+: hwmod: revise hardreset behavior
Change the way that hardreset lines are handled by the hwmod code.
Hardreset lines are generally associated with initiator IP blocks.
Prior to this change, the hwmod code expected to control hardreset
lines itself, asserting them on shutdown and deasserting them upon
enable. But driver authors inside TI have commented to us that their
drivers require direct control over these lines. Unfortunately, these
drivers haven't been posted publicly yet, so it's hard to determine
exactly what is needed, a priori. This change attempts to set forth
some reasonable semantics that should be an improvement over the
current code.
The semantics implemented by this patch are as follows:
- If the hwmod is not marked with HWMOD_INIT_NO_RESET, then assert all
associated hardreset lines during IP block setup. This is intended
to place the IP blocks into a known state that will not interfere
with other devices during kernel boot.
- IP blocks with hardreset lines will not be automatically enabled or
idled during setup. Instead, they will be left in the INITIALIZED
state.
- When the hwmod code is asked to enable, idle, or shutdown an IP
block with asserted hardreset lines, the hwmod code will do nothing.
The driver integration code must do the remaining work needed to
control these IP blocks. Once this driver integration code is posted
to the lists, hopefully we can consolidate it and move it inside the
hwmod code.
Custom reset functions for IP blocks with hardreset lines still should
be supported and are strongly endorsed. It is intended that every
subsystem with hardreset lines should have a custom reset function
that can place their subsystem into quiescent idle with the hardreset
lines deasserted.
This reverts most of commit 5365efbe29250a227502256cc912351fe2157b42
("OMAP: hwmod: Add hardreset management support"). Later code
reorganizations caused the sequencing of the code from this patch to
be changed, anyway.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoît Cousson <b-cousson@ti.com>
1 file changed