From mboxrd@z Thu Jan 1 00:00:00 1970 From: ulf.hansson@stericsson.com (Ulf Hansson) Date: Thu, 21 Mar 2013 14:48:12 +0100 Subject: [PATCH V2 2/3] clk: Improve errorhandling for clk_set_parent In-Reply-To: <1363873693-30902-1-git-send-email-ulf.hansson@stericsson.com> References: <1363873693-30902-1-git-send-email-ulf.hansson@stericsson.com> Message-ID: <1363873693-30902-3-git-send-email-ulf.hansson@stericsson.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Ulf Hansson By verifying all the needed static information before doing the clk notifications, we minimize number of unwanted rollback notifications with ABORT_RATE_CHANGE message to occur. Additionally make sure the parent are valid pointer before using it. Signed-off-by: Ulf Hansson --- drivers/clk/clk.c | 48 +++++++++++++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 19 deletions(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index d73fb0f..c7eb0d7 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1269,15 +1269,10 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) __clk_recalc_rates(clk, POST_RATE_CHANGE); } -static int __clk_set_parent(struct clk *clk, struct clk *parent) +static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent) { - struct clk *old_parent; - unsigned long flags; - int ret = -EINVAL; u8 i; - old_parent = clk->parent; - if (!clk->parents) clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents), GFP_KERNEL); @@ -1297,11 +1292,14 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) } } - if (i == clk->num_parents) { - pr_debug("%s: clock %s is not a possible parent of clock %s\n", - __func__, parent->name, clk->name); - goto out; - } + return i; +} + +static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index) +{ + unsigned long flags; + int ret; + struct clk *old_parent = clk->parent; /* migrate prepare and enable */ if (clk->prepare_count) @@ -1314,7 +1312,7 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) spin_unlock_irqrestore(&enable_lock, flags); /* change clock input source */ - ret = clk->ops->set_parent(clk->hw, i); + ret = clk->ops->set_parent(clk->hw, p_index); /* clean up old prepare and enable */ spin_lock_irqsave(&enable_lock, flags); @@ -1325,7 +1323,6 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) if (clk->prepare_count) __clk_unprepare(old_parent); -out: return ret; } @@ -1344,8 +1341,9 @@ out: int clk_set_parent(struct clk *clk, struct clk *parent) { int ret = 0; + u8 p_index; - if (!clk || !clk->ops) + if (!clk || !clk->ops || !parent) return -EINVAL; if (!clk->ops->set_parent) @@ -1357,6 +1355,21 @@ int clk_set_parent(struct clk *clk, struct clk *parent) if (clk->parent == parent) goto out; + /* check that we are allowed to re-parent if the clock is in use */ + if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) { + ret = -EBUSY; + goto out; + } + + /* try finding the new parent index */ + p_index = clk_fetch_parent_index(clk, parent); + if (p_index == clk->num_parents) { + pr_debug("%s: clock %s is not a possible parent of clock %s\n", + __func__, parent->name, clk->name); + ret = -EINVAL; + goto out; + } + /* propagate PRE_RATE_CHANGE notifications */ if (clk->notifier_count) ret = __clk_speculate_rates(clk, parent->rate); @@ -1365,11 +1378,8 @@ int clk_set_parent(struct clk *clk, struct clk *parent) if (ret == NOTIFY_STOP) goto out; - /* only re-parent if the clock is not in use */ - if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) - ret = -EBUSY; - else - ret = __clk_set_parent(clk, parent); + /* do the re-parent */ + ret = __clk_set_parent(clk, parent, p_index); /* propagate ABORT_RATE_CHANGE if .set_parent failed */ if (ret) { -- 1.7.10