Kevin, I am using linux-omap pm-2.6.29 <http://git.kernel.org/?p=linux/kernel/git/khilman/linux-omap-pm.git;a=s hortlog;h=pm-2.6.29> branch,found a dead lock condition in: arch/arm/plat-omap/resource.c->resource_release(). The dead lock happens when using resource_request("vdd1_opp",&dev,...) and resource_release("vdd1_opp", &dev) to set and release vdd1 opp constraint. The scenario is: plat-omap/resource.c/resource_release("vdd1_opp", &dev)==>resource.c/update_resource_level()=>mach-omap2/resource34xx.c/se t_opp(). In set_opp(), if the target_level of vdd1 is less than OPP3,will release the constraint set on VDD2 by calling resource_release(), but it will never return because can not get the mutex which is holding by the previous caller. int resource_release(const char *name, struct device *dev) { ....... down(&res_mutex); ........ /* Recompute and set the current level for the resource */ ret = update_resource_level(resp); res_unlock: up(&res_mutex); return ret; } int set_opp(struct shared_resource *resp, u32 target_level) { ..... if (resp == vdd1_resp) { if (target_level < 3) resource_release("vdd2_opp", &vdd2_dev); } The patch to fix this issue is below, will you pls review it and let me know your feedback? From: Limei Wang <e12499@xxxxxxxxxxxx> Date: Fri, 7 Aug 2009 11:40:35 -0500 Subject: [PATCH] OMAP PM: Fix dead lock bug in resourc_release(vdd1_opp). Signed-off-by: Limei Wang <e12499@xxxxxxxxxxxx> --- arch/arm/plat-omap/resource.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm/plat-omap/resource.c b/arch/arm/plat-omap/resource.c index ec31727..876fd12 100644 --- a/arch/arm/plat-omap/resource.c +++ b/arch/arm/plat-omap/resource.c @@ -418,10 +418,12 @@ int resource_release(const char *name, struct device *dev) list_del(&user->node); free_user(user); - /* Recompute and set the current level for the resource */ - ret = update_resource_level(resp); res_unlock: up(&res_mutex); + + /* Recompute and set the current level for the resource */ + if (!ret) + ret = update_resource_level(resp); return ret; } EXPORT_SYMBOL(resource_release); -- 1.5.6.3 Thanks, Limei -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
