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[U-Boot,4/5] Move PLL power-up from power init to memory init

Message ID 1421841318-3014-5-git-send-email-gruss@tss-engineering.com
State Changes Requested
Delegated to: Stefano Babic
Headers show

Commit Message

Graeme Russ Jan. 21, 2015, 11:55 a.m. UTC 
mxs_power_clock2pll() does not actually switch the CPU clock to the PLL.
All it does is power-up the PLL and set the CLKCTRL_CLKSEQ_BYPASS_CPU bit
(which was already set by mxs_power_clock2xtal() anyway)

spl_mem_init.c sets up the fractional divisor (which is required to run
the CPU from the PLL) and clears the CLKCTRL_CLKSEQ_BYPASS_CPU bit (which
switches the CPU clock to the PLL)

It makes more sense to power-up the PLL in spl_mem_init.c. While moving
the PLL power-up, we may as well properly configure how the PLL lock is
started and confirmed

Signed-off-by: Graeme Russ <gruss@tss-engineering.com>
---

 arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c   | 31 ++++++++++++++++++++
 arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 45 -----------------------------
 2 files changed, 31 insertions(+), 45 deletions(-)

Comments

Marek Vasut Jan. 21, 2015, 11:33 p.m. UTC | #1 
On Wednesday, January 21, 2015 at 12:55:17 PM, Graeme Russ wrote:
> mxs_power_clock2pll() does not actually switch the CPU clock to the PLL.
> All it does is power-up the PLL and set the CLKCTRL_CLKSEQ_BYPASS_CPU bit
> (which was already set by mxs_power_clock2xtal() anyway)
> 
> spl_mem_init.c sets up the fractional divisor (which is required to run
> the CPU from the PLL) and clears the CLKCTRL_CLKSEQ_BYPASS_CPU bit (which
> switches the CPU clock to the PLL)
> 
> It makes more sense to power-up the PLL in spl_mem_init.c. While moving
> the PLL power-up, we may as well properly configure how the PLL lock is
> started and confirmed
> 
> Signed-off-by: Graeme Russ <gruss@tss-engineering.com>
> ---
> 
>  arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c   | 31 ++++++++++++++++++++
>  arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 45
> ----------------------------- 2 files changed, 31 insertions(+), 45
> deletions(-)
> 
> diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c index a744e5d..af4ed8c 100644
> --- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> +++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> @@ -340,10 +340,41 @@ static void mx28_mem_init(void)
>  }
>  #endif
> 
> +/**
> + * mxs_mem_powerup_pll() - Powerup PLL0
> + *
> + * This function turns on power to PLL0. The CPU clock will be switched to
> + * PLL0 after the fractional divider and SDRAM have been configured.
> + */
> +static void mxs_mem_powerup_pll(void)
> +{
> +	struct mxs_clkctrl_regs *clkctrl_regs =
> +		(struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE;
> +
> +	/* Power up PLL0 */
> +	debug("SPL: Powering up PLL0\n");
> +	setbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl0,
> +		     CLKCTRL_PLL0CTRL0_POWER);
> +
> +	/* Toggle FORCE_LOCK to initiate the PLL lock procedure */
> +	setbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl1,
> +		     CLKCTRL_PLL0CTRL1_FORCE_LOCK);

Are you positive that this write really hits the hardware ? You might
want to read the register back before issuing another write to it.

> +	clrbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl1,
> +		     CLKCTRL_PLL0CTRL1_FORCE_LOCK);
> +
> +	/* Wait until the PLL has a stable lock - takes ~50us */
> +	while (!(readl(&clkctrl_regs->hw_clkctrl_pll0ctrl1) &
> +		 CLKCTRL_PLL0CTRL1_LOCK))
> +		;

Use mxs_wait_mask_ here I'd say.
[...]
diff mbox

Patch

diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
index a744e5d..af4ed8c 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
@@ -340,10 +340,41 @@  static void mx28_mem_init(void)
 }
 #endif
 
+/**
+ * mxs_mem_powerup_pll() - Powerup PLL0
+ *
+ * This function turns on power to PLL0. The CPU clock will be switched to
+ * PLL0 after the fractional divider and SDRAM have been configured.
+ */
+static void mxs_mem_powerup_pll(void)
+{
+	struct mxs_clkctrl_regs *clkctrl_regs =
+		(struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE;
+
+	/* Power up PLL0 */
+	debug("SPL: Powering up PLL0\n");
+	setbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl0,
+		     CLKCTRL_PLL0CTRL0_POWER);
+
+	/* Toggle FORCE_LOCK to initiate the PLL lock procedure */
+	setbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl1,
+		     CLKCTRL_PLL0CTRL1_FORCE_LOCK);
+
+	clrbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl1,
+		     CLKCTRL_PLL0CTRL1_FORCE_LOCK);
+
+	/* Wait until the PLL has a stable lock - takes ~50us */
+	while (!(readl(&clkctrl_regs->hw_clkctrl_pll0ctrl1) &
+		 CLKCTRL_PLL0CTRL1_LOCK))
+		;
+}
+
 void mxs_mem_init(void)
 {
 	early_delay(11000);
 
+	mxs_mem_powerup_pll();
+
 	mxs_mem_init_clock();
 
 	mxs_mem_setup_vdda();
diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
index e469381..7267fd5 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
@@ -50,39 +50,6 @@  static void mxs_power_clock2xtal(void)
 }
 
 /**
- * mxs_power_clock2pll() - Switch CPU core clock source to PLL
- *
- * This function switches the CPU core clock from 24MHz XTAL oscilator
- * to PLL. This can only be called once the PLL has re-locked and once
- * the PLL is stable after reconfiguration.
- */
-static void mxs_power_clock2pll(void)
-{
-	struct mxs_clkctrl_regs *clkctrl_regs =
-		(struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE;
-
-	debug("SPL: Switching CPU core clock source to PLL\n");
-
-	/*
-	 * TODO: Are we really? It looks like we turn on PLL0, but we then
-	 * set the CLKCTRL_CLKSEQ_BYPASS_CPU bit of the (which was already
-	 * set by mxs_power_clock2xtal()). Clearing this bit here seems to
-	 * introduce some instability (causing the CPU core to hang). Maybe
-	 * we aren't giving PLL0 enough time to stabilise?
-	 */
-	setbits_le32(&clkctrl_regs->hw_clkctrl_pll0ctrl0,
-			CLKCTRL_PLL0CTRL0_POWER);
-	early_delay(100);
-
-	/*
-	 * TODO: Should the PLL0 FORCE_LOCK bit be set here followed be a
-	 * wait on the PLL0 LOCK bit?
-	 */
-	setbits_le32(&clkctrl_regs->hw_clkctrl_clkseq,
-			CLKCTRL_CLKSEQ_BYPASS_CPU);
-}
-
-/**
  * mxs_power_set_auto_restart() - Set the auto-restart bit
  *
  * This function ungates the RTC block and sets the AUTO_RESTART
@@ -993,12 +960,6 @@  static void mxs_power_configure_power_source(void)
 			BATTERY_BRWNOUT_BITFIELD_VALUE <<
 			POWER_BATTMONITOR_BRWNOUT_LVL_OFFSET);
 	mxs_5v_boot();
-
-	/*
-	 * TODO: Do not switch CPU clock to PLL if we are VDD5V is sourced
-	 * from USB VBUS
-	 */
-	mxs_power_clock2pll();
 #else
 	if (readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO) {
 		batt_ready = mxs_is_batt_ready();
@@ -1021,12 +982,6 @@  static void mxs_power_configure_power_source(void)
 		mxs_batt_boot();
 	}
 
-	/*
-	 * TODO: Do not switch CPU clock to PLL if we are VDD5V is sourced
-	 * from USB VBUS
-	 */
-	mxs_power_clock2pll();
-
 	mxs_init_batt_bo();
 #endif