The goal here is to support inheriting a display setup by bootloader,
although there may also be some non-display related use-cases.
Rough idea is to add a flag for clks and power domains that might
already be enabled when kernel starts, and make corresponding fixups
to clk enable/prepare_count and power-domain state so that these are
not automatically disabled late in boot.
If bootloader is enabling display, and kernel is using efifb before
real display driver is loaded (potentially from kernel module after
userspace starts, in a typical distro kernel), we don't want to kill
the clocks and power domains that are used by the display before
userspace starts.
Second part is for drm/msm to check if display related clocks are
enabled when it is loaded, and if so read back hw state to sync
existing display state w/ software state, and skip the initial
clk_enable's and otherwise fixing up clk/regulator/etc ref counts
(skipping the normal display-enable codepaths), therefore inheriting
the enable done by bootloader.
Obviously this should be split up into multiple patches and many
TODOs addressed. But I guess this is enough for now to start
discussing the approach, and in particular how drm and clock/pd
drivers work together to handle handover from bootloader.
The CLK_INHERIT_BOOTLOADER and related gsdc flag should only be set
on leaf nodes.
---
drivers/clk/clk.c | 18 ++++++++++++++++++
drivers/clk/qcom/common.c | 28 ++++++++++++++++++++++++++++
drivers/clk/qcom/gcc-msm8916.c | 15 ++++++++-------
drivers/clk/qcom/gdsc.c | 6 ++++++
drivers/clk/qcom/gdsc.h | 1 +
include/linux/clk-provider.h | 1 +
include/linux/clk.h | 9 +++++++++
7 files changed, 71 insertions(+), 7 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index fc58c52a26b4..7c84e8d6e816 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -796,6 +796,24 @@ static void clk_disable_unused_subtree(struct clk_core *core)
clk_core_disable_unprepare(core->parent);
}
+/* clock and it's parents are already prepared/enabled from bootloader,
+ * so simply record the fact.
+ */
+static void __clk_inherit_enabled(struct clk_core *core)
+{
+ core->enable_count++;
+ core->prepare_count++;
+if (core->hw->init->name) // XXX hack.. something funny with xo/xo_board..
+ if (core->parent)
+ __clk_inherit_enabled(core->parent);
+}
+
+void clk_inherit_enabled(struct clk *clk)
+{
+ __clk_inherit_enabled(clk->core);
+}
+EXPORT_SYMBOL_GPL(clk_inherit_enabled);
+
static bool clk_ignore_unused;
static int __init clk_ignore_unused_setup(char *__unused)
{
diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
index d523991c945f..90b698c910d0 100644
--- a/drivers/clk/qcom/common.c
+++ b/drivers/clk/qcom/common.c
@@ -11,6 +11,7 @@
* GNU General Public License for more details.
*/
+#include <linux/clk.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/regmap.h>
@@ -258,6 +259,33 @@ int qcom_cc_really_probe(struct platform_device *pdev,
if (ret)
return ret;
+ /* Check which of clocks that we inherit state from bootloader
+ * are enabled, and fixup enable/prepare state (as well as that
+ * of it's parents).
+ *
+ * TODO can we assume that parents coming from another clk
+ * driver are already registered?
+ */
+ for (i = 0; i < num_clks; i++) {
+ struct clk_hw *hw;
+
+ if (!rclks[i])
+ continue;
+
+ hw = &rclks[i]->hw;
+
+ if (!(hw->init->flags & CLK_INHERIT_BOOTLOADER))
+ continue;
+
+ if (!clk_is_enabled_regmap(hw))
+ continue;
+
+ dev_dbg(dev, "%s is enabled from bootloader!\n",
+ hw->init->name);
+
+ clk_inherit_enabled(hw->clk);
+ }
+
reset = &cc->reset;
reset->rcdev.of_node = dev->of_node;
reset->rcdev.ops = &qcom_reset_ops;
diff --git a/drivers/clk/qcom/gcc-msm8916.c b/drivers/clk/qcom/gcc-msm8916.c
index 2cfe7000fc60..c939d33f6377 100644
--- a/drivers/clk/qcom/gcc-msm8916.c
+++ b/drivers/clk/qcom/gcc-msm8916.c
@@ -2468,7 +2468,7 @@ static struct clk_branch gcc_mdss_ahb_clk = {
"pcnoc_bfdcd_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2485,7 +2485,7 @@ static struct clk_branch gcc_mdss_axi_clk = {
"system_noc_bfdcd_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2502,7 +2502,7 @@ static struct clk_branch gcc_mdss_byte0_clk = {
"byte0_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2519,7 +2519,7 @@ static struct clk_branch gcc_mdss_esc0_clk = {
"esc0_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2536,7 +2536,7 @@ static struct clk_branch gcc_mdss_mdp_clk = {
"mdp_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2553,7 +2553,7 @@ static struct clk_branch gcc_mdss_pclk0_clk = {
"pclk0_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -2570,7 +2570,7 @@ static struct clk_branch gcc_mdss_vsync_clk = {
"vsync_clk_src",
},
.num_parents = 1,
- .flags = CLK_SET_RATE_PARENT,
+ .flags = CLK_SET_RATE_PARENT | CLK_INHERIT_BOOTLOADER,
.ops = &clk_branch2_ops,
},
},
@@ -3060,6 +3060,7 @@ static struct gdsc mdss_gdsc = {
.name = "mdss",
},
.pwrsts = PWRSTS_OFF_ON,
+ .flags = INHERIT_BL,
};
static struct gdsc jpeg_gdsc = {
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index a4f3580587b7..440d819b2d9d 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -291,6 +291,12 @@ static int gdsc_init(struct gdsc *sc)
if ((sc->flags & VOTABLE) && on)
gdsc_enable(&sc->pd);
+ if ((sc->flags & INHERIT_BL) && on) {
+ pr_debug("gdsc: %s is enabled from bootloader!\n", sc->pd.name);
+ gdsc_enable(&sc->pd);
+ sc->pd.flags |= GENPD_FLAG_ALWAYS_ON;
+ }
+
if (on || (sc->pwrsts & PWRSTS_RET))
gdsc_force_mem_on(sc);
else
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 39648348e5ec..3b5e64b060c2 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -53,6 +53,7 @@ struct gdsc {
#define VOTABLE BIT(0)
#define CLAMP_IO BIT(1)
#define HW_CTRL BIT(2)
+#define INHERIT_BL BIT(3)
struct reset_controller_dev *rcdev;
unsigned int *resets;
unsigned int reset_count;
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index c59c62571e4f..4d5505f92329 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -35,6 +35,7 @@
#define CLK_IS_CRITICAL BIT(11) /* do not gate, ever */
/* parents need enable during gate/ungate, set rate and re-parent */
#define CLK_OPS_PARENT_ENABLE BIT(12)
+#define CLK_INHERIT_BOOTLOADER BIT(13) /* clk may be enabled from bootloader */
struct clk;
struct clk_hw;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 91bd464f4c9b..461991fc57e2 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -391,6 +391,15 @@ void clk_disable(struct clk *clk);
void clk_bulk_disable(int num_clks, const struct clk_bulk_data *clks);
/**
+ * clk_inherit_enabled - update the enable/prepare count of a clock and it's
+ * parents for clock enabled by bootloader.
+ *
+ * Intended to be used by clock drivers to inform the clk core of a clock
+ * that is already running.
+ */
+void clk_inherit_enabled(struct clk *clk);
+
+/**
* clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
* This is only valid once the clock source has been enabled.
* @clk: clock source
--
2.13.0
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