diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.4/950-0216-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.4/950-0216-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0216-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch b/target/linux/bcm27xx/patches-5.4/950-0216-clk-bcm2835-Add-support-for-setting-leaf-clock-rates.patch new file mode 100644 index 0000000000..3227f8c914 --- /dev/null +++ b/target/linux/bcm27xx/patches-5.4/950-0216-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 +@@ -1114,15 +1114,19 @@ 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); + +@@ -1494,7 +1498,7 @@ 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. |