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Diffstat (limited to 'target/linux/bcm27xx/patches-5.4/950-0220-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch')
-rw-r--r--target/linux/bcm27xx/patches-5.4/950-0220-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch53
1 files changed, 53 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0220-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch b/target/linux/bcm27xx/patches-5.4/950-0220-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch
new file mode 100644
index 0000000000..056dc69ae7
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0220-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch
@@ -0,0 +1,53 @@
+From cfe0832e8306cd9955f682b7314a5a6fc3b9d514 Mon Sep 17 00:00:00 2001
+From: Eric Anholt <eric@anholt.net>
+Date: Thu, 2 May 2019 15:11:05 -0700
+Subject: [PATCH] clk: bcm2835: Add support for setting leaf clock
+ rates while running.
+
+As long as you wait for !BUSY, you can do glitch-free updates of clock
+rate while the clock is running.
+
+Signed-off-by: Eric Anholt <eric@anholt.net>
+---
+ drivers/clk/bcm/clk-bcm2835.c | 22 +++++++++++++---------
+ 1 file changed, 13 insertions(+), 9 deletions(-)
+
+--- a/drivers/clk/bcm/clk-bcm2835.c
++++ b/drivers/clk/bcm/clk-bcm2835.c
+@@ -1098,15 +1098,19 @@ static int bcm2835_clock_set_rate(struct
+
+ spin_lock(&cprman->regs_lock);
+
+- /*
+- * Setting up frac support
+- *
+- * In principle it is recommended to stop/start the clock first,
+- * but as we set CLK_SET_RATE_GATE during registration of the
+- * clock this requirement should be take care of by the
+- * clk-framework.
++ ctl = cprman_read(cprman, data->ctl_reg);
++
++ /* If the clock is running, we have to pause clock generation while
++ * updating the control and div regs. This is glitchless (no clock
++ * signals generated faster than the rate) but each reg access is two
++ * OSC cycles so the clock will slow down for a moment.
+ */
+- ctl = cprman_read(cprman, data->ctl_reg) & ~CM_FRAC;
++ if (ctl & CM_ENABLE) {
++ cprman_write(cprman, data->ctl_reg, ctl & ~CM_ENABLE);
++ bcm2835_clock_wait_busy(clock);
++ }
++
++ ctl &= ~CM_FRAC;
+ ctl |= (div & CM_DIV_FRAC_MASK) ? CM_FRAC : 0;
+ cprman_write(cprman, data->ctl_reg, ctl);
+
+@@ -1476,7 +1480,7 @@ static struct clk_hw *bcm2835_register_c
+ init.ops = &bcm2835_vpu_clock_clk_ops;
+ } else {
+ init.ops = &bcm2835_clock_clk_ops;
+- init.flags |= CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
++ init.flags |= CLK_SET_PARENT_GATE;
+
+ /* If the clock wasn't actually enabled at boot, it's not
+ * critical.