arm: imx: correct the hardware clock gate setting for shared nodes
Subsystems (3)
PATCH v2 1/1 arm: imx: correct the hardware clock gate setting for shared nodes
For those clk gates which hold share count, since its is_enabled callback is only checking the share count rather than reading the hardware register setting, in the late phase of kernel bootup, the clk_disable_unused action will NOT handle the scenario of share_count is 0 but the hardware setting is enabled, actually, uboot normally enables all clk gates, then those shared clk gates will be always enabled until they are used by some modules.
So the problem would be: when kernel boot up, the usecount cat from clk tree is 0, but the clk gates actually is enabled in hardware register, it will confuse user and bring unnecessary power consumption.
This patch adds .disable_unused callback to handle such scenario in late phase of kernel boot up, then the hardware status will match the clk tree info.
---
changes from V1:
handle such issue via clk-gate2 framework to fulfill all
i.mx6 platforms, introduced .disable_unused callback.
arch/arm/mach-imx/clk-gate2.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
arch/arm/mach-imx/clk-gate2.c +20 -4
@@ -96,15 +96,31 @@ static int clk_gate2_is_enabled(struct clk_hw *hw) {struct clk_gate2 *gate =to_clk_gate2 (hw); -if (gate->share_count) -return !!__clk_get_enable_count (hw->clk); -else -return clk_gate2_reg_is_enabled (gate->reg, gate->bit_idx); +return clk_gate2_reg_is_enabled (gate->reg, gate->bit_idx); +} + +static void clk_gate2_disable_unused (struct clk_hw *hw) +{ +struct clk_gate2 *gate =to_clk_gate2 (hw); +unsigned long flags =0 ; +u32 reg; + +spin_lock_irqsave (gate->lock, flags); + +if ((gate->share_count && *gate->share_count ==0 ) || + !gate->share_count) { + reg =readl (gate->reg); + reg &= ~(3 << gate->bit_idx); +writel (reg, gate->reg); + } + +spin_unlock_irqrestore (gate->lock, flags); }static struct clk_ops clk_gate2_ops = { .enable = clk_gate2_enable, .disable = clk_gate2_disable, + .disable_unused = clk_gate2_disable_unused, .is_enabled = clk_gate2_is_enabled, };
Signature · 1 line
1.7.9.5
PATCH v2 1/1 arm: imx: correct the hardware clock gate setting for shared nodes
Hello,
Quoted 6 lines · Anson Huang
For those clk gates which hold share count, since its
is_enabledcallback is only checking the share count rather than reading the hardware register setting, in the late phase of kernel bootup, theclk_disable_unusedaction will NOT handle the scenario ofshare_countis 0 but the hardware setting is enabled, actually, uboot normally enables all clk gates, then those shared clk gates
still s/uboot/U-Boot/
Quoted 24 lines
will be always enabled until they are used by some modules.
So the problem would be: when kernel boot up, the usecount cat from clk tree is 0, but the clk gates actually is enabled in hardware register, it will confuse user and bring unnecessary power consumption.
This patch adds .disable_unused callback to handle such scenario in late phase of kernel boot up, then the hardware status will match the clk tree info.
Signed-off-by Anson Huang <[email protected]>---
changes from V1:
handle such issue via clk-gate2 framework to fulfill all
i.mx6 platforms, introduced .disable_unused callback.arch/arm/mach-imx/clk-gate2.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)arch/arm/mach-imx/clk-gate2.c +0
-0
arch/arm/mach-imx/clk-gate2.c static int clk_gate2_is_enabled(struct clk_hw *hw) · line 99
Quoted 8 lines
arch/arm/mach-imx/clk-gate2.c +1
-4@@ -96,15 +96,31 @@ static int clk_gate2_is_enabled(struct clk_hw *hw) {struct clk_gate2 *gate =to_clk_gate2 (hw); -if (gate->share_count) -return !!__clk_get_enable_count (hw->clk); -else -return clk_gate2_reg_is_enabled (gate->reg, gate->bit_idx); +return clk_gate2_reg_is_enabled (gate->reg, gate->bit_idx);
point out in the commit log that this is changed.
arch/arm/mach-imx/clk-gate2.c static int clk_gate2_is_enabled(struct clk_hw *hw) · line 111
Quoted 12 lines
arch/arm/mach-imx/clk-gate2.c +12
-0+} + +static void clk_gate2_disable_unused (struct clk_hw *hw) +{ +struct clk_gate2 *gate =to_clk_gate2 (hw); +unsigned long flags =0 ; +u32 reg; + +spin_lock_irqsave (gate->lock, flags); + +if ((gate->share_count && *gate->share_count ==0 ) || + !gate->share_count) {
That's equivalent to the simpler expression
if (!gate->share_count || *gate->share_count == 0)
Other than that it doesn't make the status quo worse, still I'd prefer a nicer model for these shared clocks.
Best regards
Uwe
Signature · 2 lines
Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ |