diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0347-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0347-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0347-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch b/target/linux/brcm2708/patches-4.4/0347-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch new file mode 100644 index 0000000000..cc90841566 --- /dev/null +++ b/target/linux/brcm2708/patches-4.4/0347-clk-bcm2835-Skip-PLLC-clocks-when-deciding-on-a-new-.patch @@ -0,0 +1,71 @@ +From 960587a39d7ca3d5279841218b42e008df7194aa Mon Sep 17 00:00:00 2001 +From: Eric Anholt <eric@anholt.net> +Date: Tue, 26 Apr 2016 12:39:45 -0700 +Subject: [PATCH] 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); |