diff options
Diffstat (limited to 'target/linux/ipq806x/patches-4.4/135-clk-Avoid-sending-high-rates-to-downstream-clocks-du.patch')
| -rw-r--r-- | target/linux/ipq806x/patches-4.4/135-clk-Avoid-sending-high-rates-to-downstream-clocks-du.patch | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/target/linux/ipq806x/patches-4.4/135-clk-Avoid-sending-high-rates-to-downstream-clocks-du.patch b/target/linux/ipq806x/patches-4.4/135-clk-Avoid-sending-high-rates-to-downstream-clocks-du.patch deleted file mode 100644 index 5015d32d86..0000000000 --- a/target/linux/ipq806x/patches-4.4/135-clk-Avoid-sending-high-rates-to-downstream-clocks-du.patch +++ /dev/null @@ -1,122 +0,0 @@ -From 39d42ce5031d2a4f92fa203b87acfbab340b15a2 Mon Sep 17 00:00:00 2001 -From: Stephen Boyd <sboyd@codeaurora.org> -Date: Fri, 20 Mar 2015 23:45:22 -0700 -Subject: [PATCH 2/2] clk: Avoid sending high rates to downstream clocks during - set_rate - -If a clock is on and we call clk_set_rate() on it we may get into -a situation where the clock temporarily increases in rate -dramatically while we walk the tree and call .set_rate() ops. For -example, consider a case where a PLL feeds into a divider. -Initially the divider is set to divide by 1 and the PLL is -running fairly slow (100MHz). The downstream consumer of the -divider output can only handle rates =< 400 MHz, but the divider -can only choose between divisors of 1 and 4. - - +-----+ +----------------+ - | PLL |-->| div 1 or div 4 |---> consumer device - +-----+ +----------------+ - -To achieve a rate of 400MHz on the output of the divider, we -would have to set the rate of the PLL to 1.6 GHz and then divide -it by 4. The current code would set the PLL to 1.6GHz first while -the divider is still set to 1, thus causing the downstream -consumer of the clock to receive a few clock cycles of 1.6GHz -clock (far beyond it's maximum acceptable rate). We should be -changing the divider first before increasing the PLL rate to -avoid this problem. - -Therefore, set the rate of any child clocks that are increasing -in rate from their current rate so that they can increase their -dividers if necessary. We assume that there isn't such a thing as -minimum rate requirements. - -Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> -Signed-off-by: Ram Chandra Jangir <rjangi@codeaurora.org> ---- - drivers/clk/clk.c | 34 ++++++++++++++++++++++------------ - 1 file changed, 22 insertions(+), 12 deletions(-) - ---- a/drivers/clk/clk.c -+++ b/drivers/clk/clk.c -@@ -1427,21 +1427,24 @@ static struct clk_core *clk_propagate_ra - * walk down a subtree and set the new rates notifying the rate - * change on the way - */ --static void clk_change_rate(struct clk_core *core) -+static void -+clk_change_rate(struct clk_core *core, unsigned long best_parent_rate) - { - struct clk_core *child; - struct hlist_node *tmp; - unsigned long old_rate; -- unsigned long best_parent_rate = 0; - bool skip_set_rate = false; - struct clk_core *old_parent; - -- old_rate = core->rate; -+ hlist_for_each_entry(child, &core->children, child_node) { -+ /* Skip children who will be reparented to another clock */ -+ if (child->new_parent && child->new_parent != core) -+ continue; -+ if (child->new_rate > child->rate) -+ clk_change_rate(child, core->new_rate); -+ } - -- if (core->new_parent) -- best_parent_rate = core->new_parent->rate; -- else if (core->parent) -- best_parent_rate = core->parent->rate; -+ old_rate = core->rate; - - if (core->new_parent && core->new_parent != core->parent) { - old_parent = __clk_set_parent_before(core, core->new_parent); -@@ -1467,7 +1470,7 @@ static void clk_change_rate(struct clk_c - - trace_clk_set_rate_complete(core, core->new_rate); - -- core->rate = clk_recalc(core, best_parent_rate); -+ core->rate = core->new_rate; - - if (core->notifier_count && old_rate != core->rate) - __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate); -@@ -1483,12 +1486,13 @@ static void clk_change_rate(struct clk_c - /* Skip children who will be reparented to another clock */ - if (child->new_parent && child->new_parent != core) - continue; -- clk_change_rate(child); -+ if (child->new_rate != child->rate) -+ clk_change_rate(child, core->new_rate); - } - - /* handle the new child who might not be in core->children yet */ -- if (core->new_child) -- clk_change_rate(core->new_child); -+ if (core->new_child && core->new_child->new_rate != core->new_child->rate) -+ clk_change_rate(core->new_child, core->new_rate); - } - - static int clk_core_set_rate_nolock(struct clk_core *core, -@@ -1497,6 +1501,7 @@ static int clk_core_set_rate_nolock(stru - struct clk_core *top, *fail_clk; - unsigned long rate = req_rate; - int ret = 0; -+ unsigned long parent_rate; - - if (!core) - return 0; -@@ -1522,8 +1527,13 @@ static int clk_core_set_rate_nolock(stru - return -EBUSY; - } - -+ if (top->parent) -+ parent_rate = top->parent->rate; -+ else -+ parent_rate = 0; -+ - /* change the rates */ -- clk_change_rate(top); -+ clk_change_rate(top, parent_rate); - - core->req_rate = req_rate; - |