[PATCH 2/3] ASoC: qcom: q6dsp-lpass-clocks: Restore clocks after a DSP restart
From: Shawn Guo
Date: Sat Nov 14 2026 - 22:21:21 EST
The DSP forgets all clock requests and votes when it stops. A consumer
that still holds a clock prepared across a DSP restart then holds a
clock that the DSP no longer provides, and its later unprepare releases
a request the DSP never saw.
Track which clocks are prepared, and add q6dsp_clock_dsp_down() and
q6dsp_clock_dsp_up() for the DSP service driver to call when the DSP
goes away and comes back. dsp_down() marks the prepared clocks as lost.
dsp_up() requests them again at their current rate, or votes for them
again. Unpreparing a lost clock skips the release, since the DSP holds
nothing for it.
Fold the prepare/unprepare ops of rate and vote clocks into one pair,
so both kinds share the request/release helpers used by the restore
path. A mutex serializes prepare/unprepare against dsp_down/up.
This patch does not change behaviour on its own: no driver calls the
new functions yet.
Signed-off-by: Shawn Guo <shengchao.guo@xxxxxxxxxxxxxxxx>
---
sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.c | 147 ++++++++++++++++++----
sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.h | 2 +
2 files changed, 123 insertions(+), 26 deletions(-)
diff --git a/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.c b/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.c
index 94d96130245e..22d3f3c6d46f 100644
--- a/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.c
+++ b/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.c
@@ -7,6 +7,7 @@
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
+#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <dt-bindings/sound/qcom,q6dsp-lpass-ports.h>
@@ -22,6 +23,10 @@ struct q6dsp_clk {
int attributes;
int rate;
uint32_t handle;
+ bool vote;
+ bool prepared;
+ /* Still prepared, but dropped by the DSP when it stopped */
+ bool lost;
struct clk_hw hw;
};
@@ -29,17 +34,45 @@ struct q6dsp_clk {
struct q6dsp_cc {
struct device *dev;
+ /* Serializes clock requests against DSP down/up */
+ struct mutex lock;
struct q6dsp_clk *clks[Q6DSP_MAX_CLK_ID];
const struct q6dsp_clk_desc *desc;
};
+static int q6dsp_clk_request(struct q6dsp_cc *cc, struct q6dsp_clk *clk)
+{
+ if (clk->vote)
+ return cc->desc->lpass_vote_clk(clk->dev, clk->q6dsp_clk_id,
+ clk_hw_get_name(&clk->hw),
+ &clk->handle);
+
+ return cc->desc->lpass_set_clk(clk->dev, clk->q6dsp_clk_id, clk->attributes,
+ Q6DSP_LPASS_CLK_ROOT_DEFAULT, clk->rate);
+}
+
+static void q6dsp_clk_release(struct q6dsp_cc *cc, struct q6dsp_clk *clk)
+{
+ if (clk->vote)
+ cc->desc->lpass_unvote_clk(clk->dev, clk->q6dsp_clk_id, clk->handle);
+ else
+ cc->desc->lpass_set_clk(clk->dev, clk->q6dsp_clk_id, clk->attributes,
+ Q6DSP_LPASS_CLK_ROOT_DEFAULT, 0);
+}
+
static int clk_q6dsp_prepare(struct clk_hw *hw)
{
struct q6dsp_clk *clk = to_q6dsp_clk(hw);
struct q6dsp_cc *cc = dev_get_drvdata(clk->dev);
+ int ret;
- return cc->desc->lpass_set_clk(clk->dev, clk->q6dsp_clk_id, clk->attributes,
- Q6DSP_LPASS_CLK_ROOT_DEFAULT, clk->rate);
+ guard(mutex)(&cc->lock);
+
+ ret = q6dsp_clk_request(cc, clk);
+ if (!ret)
+ clk->prepared = true;
+
+ return ret;
}
static void clk_q6dsp_unprepare(struct clk_hw *hw)
@@ -47,8 +80,14 @@ static void clk_q6dsp_unprepare(struct clk_hw *hw)
struct q6dsp_clk *clk = to_q6dsp_clk(hw);
struct q6dsp_cc *cc = dev_get_drvdata(clk->dev);
- cc->desc->lpass_set_clk(clk->dev, clk->q6dsp_clk_id, clk->attributes,
- Q6DSP_LPASS_CLK_ROOT_DEFAULT, 0);
+ guard(mutex)(&cc->lock);
+
+ /* A lost clock is not held by the DSP, so there is nothing to release */
+ if (!clk->lost)
+ q6dsp_clk_release(cc, clk);
+
+ clk->prepared = false;
+ clk->lost = false;
}
static int clk_q6dsp_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -83,26 +122,9 @@ static const struct clk_ops clk_q6dsp_ops = {
.recalc_rate = clk_q6dsp_recalc_rate,
};
-static int clk_vote_q6dsp_block(struct clk_hw *hw)
-{
- struct q6dsp_clk *clk = to_q6dsp_clk(hw);
- struct q6dsp_cc *cc = dev_get_drvdata(clk->dev);
-
- return cc->desc->lpass_vote_clk(clk->dev, clk->q6dsp_clk_id,
- clk_hw_get_name(&clk->hw), &clk->handle);
-}
-
-static void clk_unvote_q6dsp_block(struct clk_hw *hw)
-{
- struct q6dsp_clk *clk = to_q6dsp_clk(hw);
- struct q6dsp_cc *cc = dev_get_drvdata(clk->dev);
-
- cc->desc->lpass_unvote_clk(clk->dev, clk->q6dsp_clk_id, clk->handle);
-}
-
static const struct clk_ops clk_vote_q6dsp_ops = {
- .prepare = clk_vote_q6dsp_block,
- .unprepare = clk_unvote_q6dsp_block,
+ .prepare = clk_q6dsp_prepare,
+ .unprepare = clk_q6dsp_unprepare,
};
@@ -146,6 +168,10 @@ int q6dsp_clock_dev_probe(struct platform_device *pdev)
cc->dev = dev;
q6dsp_clks = desc->clks;
+ ret = devm_mutex_init(dev, &cc->lock);
+ if (ret)
+ return ret;
+
for (i = 0; i < desc->num_clks; i++) {
unsigned int id = q6dsp_clks[i].clk_id;
struct clk_init_data init = {
@@ -160,12 +186,13 @@ int q6dsp_clock_dev_probe(struct platform_device *pdev)
clk->dev = dev;
clk->q6dsp_clk_id = q6dsp_clks[i].q6dsp_clk_id;
clk->rate = q6dsp_clks[i].rate;
+ clk->vote = !clk->rate;
clk->hw.init = &init;
- if (clk->rate)
- init.ops = &clk_q6dsp_ops;
- else
+ if (clk->vote)
init.ops = &clk_vote_q6dsp_ops;
+ else
+ init.ops = &clk_q6dsp_ops;
cc->clks[id] = clk;
@@ -183,3 +210,71 @@ int q6dsp_clock_dev_probe(struct platform_device *pdev)
return 0;
}
EXPORT_SYMBOL_GPL(q6dsp_clock_dev_probe);
+
+/**
+ * q6dsp_clock_dsp_down() - Mark the clocks dropped by a stopped DSP
+ * @dev: clock controller device
+ *
+ * The DSP forgets all clock requests when it stops. Remember the clocks that
+ * consumers still hold prepared, so q6dsp_clock_dsp_up() can request them
+ * again once the DSP is back.
+ */
+void q6dsp_clock_dsp_down(struct device *dev)
+{
+ struct q6dsp_cc *cc;
+ int i;
+
+ guard(device)(dev);
+
+ cc = dev_get_drvdata(dev);
+ if (!cc)
+ return;
+
+ guard(mutex)(&cc->lock);
+
+ for (i = 0; i < Q6DSP_MAX_CLK_ID; i++) {
+ struct q6dsp_clk *clk = cc->clks[i];
+
+ if (clk && clk->prepared)
+ clk->lost = true;
+ }
+}
+EXPORT_SYMBOL_GPL(q6dsp_clock_dsp_down);
+
+/**
+ * q6dsp_clock_dsp_up() - Restore the clocks dropped by a stopped DSP
+ * @dev: clock controller device
+ *
+ * Request again, at their current rate, the clocks that were still prepared
+ * when the DSP stopped.
+ */
+void q6dsp_clock_dsp_up(struct device *dev)
+{
+ struct q6dsp_cc *cc;
+ int i, ret;
+
+ guard(device)(dev);
+
+ cc = dev_get_drvdata(dev);
+ if (!cc)
+ return;
+
+ guard(mutex)(&cc->lock);
+
+ for (i = 0; i < Q6DSP_MAX_CLK_ID; i++) {
+ struct q6dsp_clk *clk = cc->clks[i];
+
+ if (!clk || !clk->lost)
+ continue;
+
+ ret = q6dsp_clk_request(cc, clk);
+ if (ret) {
+ dev_err(dev, "Failed to restore %s: %d\n",
+ clk_hw_get_name(&clk->hw), ret);
+ continue;
+ }
+
+ clk->lost = false;
+ }
+}
+EXPORT_SYMBOL_GPL(q6dsp_clock_dsp_up);
diff --git a/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.h b/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.h
index 3770d81f2bd6..e4655a0b77c6 100644
--- a/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.h
+++ b/sound/soc/qcom/qdsp6/q6dsp-lpass-clocks.h
@@ -26,5 +26,7 @@ struct q6dsp_clk_desc {
};
int q6dsp_clock_dev_probe(struct platform_device *pdev);
+void q6dsp_clock_dsp_down(struct device *dev);
+void q6dsp_clock_dsp_up(struct device *dev);
#endif /* __Q6DSP_AUDIO_CLOCKS_H__ */
--
2.43.0