kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-16 22:39:48 +00:00
Code Issues Releases Packages Activity

OMAP2+: hwmod: upgrade per-hwmod mutex to a spinlock

Browse source 
Change the per-hwmod mutex to a spinlock.  (The per-hwmod lock
serializes most post-initialization hwmod operations such as enable,
idle, and shutdown.)  Spinlocks are needed, because in some cases,
hwmods must be enabled from timer interrupt disabled-context, such as
an ISR.  The current use-case that is driving this is the OMAP GPIO
block ISR: it can trigger interrupts even with its clocks disabled,
but these clocks are needed for register accesses in the ISR to succeed.

This patch also effectively reverts commit
848240223c - this patch makes
_omap_hwmod_enable() and _omap_hwmod_init() static, renames them back
to _enable() and _idle(), and changes their callers to call the
spinlocking versions.  Previously, since omap_hwmod_{enable,init}()
attempted to take mutexes, these functions could not be called while
the timer interrupt was disabled; but now that the functions use
spinlocks and save and restore the IRQ state, it is appropriate to
call them directly.

Kevin Hilman <khilman@deeprootsystems.com> originally proposed this
patch - thanks Kevin.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Benoît Cousson <b-cousson@ti.com>
This commit is contained in:
Paul Walmsley 2010-12-14 12:42:35 -07:00
commit dc6d1cda04
3 changed files with 64 additions and 56 deletions
Download patch file Download diff file Expand all files Collapse all files