summaryrefslogtreecommitdiffstats
path: root/target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch
diff options
context:
space:
mode:
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch')
-rw-r--r--target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch71
1 files changed, 71 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch b/target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch
new file mode 100644
index 0000000000..634db51224
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.4/0351-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch
@@ -0,0 +1,71 @@
+From 4ef6b916c3004783aeeabfcd9889bca046d944bf Mon Sep 17 00:00:00 2001
+From: Eric Anholt <eric@anholt.net>
+Date: Tue, 26 Apr 2016 12:39:45 -0700
+Subject: [PATCH 351/381] clk: bcm2835: Skip PLLC clocks when deciding on a new
+ clock parent
+
+If the firmware had set up a clock to source from PLLC, go along with
+it. But if we're looking for a new parent, we don't want to switch it
+to PLLC because the firmware will force PLLC (and thus the AXI bus
+clock) to different frequencies during over-temp/under-voltage,
+without notification to Linux.
+
+On my system, this moves the Linux-enabled HDMI state machine and DSI1
+escape clock over to plld_per from pllc_per. EMMC still ends up on
+pllc_per, because the firmware had set it up to use that.
+
+Signed-off-by: Eric Anholt <eric@anholt.net>
+Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the audio domain clocks")
+---
+ drivers/clk/bcm/clk-bcm2835.c | 23 +++++++++++++++++++++++
+ 1 file changed, 23 insertions(+)
+
+--- a/drivers/clk/bcm/clk-bcm2835.c
++++ b/drivers/clk/bcm/clk-bcm2835.c
+@@ -1020,16 +1020,28 @@ static int bcm2835_clock_set_rate(struct
+ return 0;
+ }
+
++static bool
++bcm2835_clk_is_pllc(struct clk_hw *hw)
++{
++ if (!hw)
++ return false;
++
++ return strncmp(clk_hw_get_name(hw), "pllc", 4) == 0;
++}
++
+ static int bcm2835_clock_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+ {
+ struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
+ struct clk_hw *parent, *best_parent = NULL;
++ bool current_parent_is_pllc;
+ unsigned long rate, best_rate = 0;
+ unsigned long prate, best_prate = 0;
+ size_t i;
+ u32 div;
+
++ current_parent_is_pllc = bcm2835_clk_is_pllc(clk_hw_get_parent(hw));
++
+ /*
+ * Select parent clock that results in the closest but lower rate
+ */
+@@ -1037,6 +1049,17 @@ static int bcm2835_clock_determine_rate(
+ parent = clk_hw_get_parent_by_index(hw, i);
+ if (!parent)
+ continue;
++
++ /*
++ * Don't choose a PLLC-derived clock as our parent
++ * unless it had been manually set that way. PLLC's
++ * frequency gets adjusted by the firmware due to
++ * over-temp or under-voltage conditions, without
++ * prior notification to our clock consumer.
++ */
++ if (bcm2835_clk_is_pllc(parent) && !current_parent_is_pllc)
++ continue;
++
+ prate = clk_hw_get_rate(parent);
+ div = bcm2835_clock_choose_div(hw, req->rate, prate, true);
+ rate = bcm2835_clock_rate_from_divisor(clock, prate, div);