On Fri Jul 31 10:54:34 2026 +0200, Loic Poulain wrote:
> Add optional PM clock support to the CAMSS driver using the PM clock
> framework. This allows CAMSS clocks to be registered once and
> automatically managed during runtime suspend and resume.
>
> This is especially useful for global CAMSS clocks that are shared across
> multiple CAMSS subblocks.
>
> This avoids the need for each subblock to reference and manage the
> shared clocks individually. A typical example is the set of clocks in
> the top_group, which may be used by CSID, PHY, CCI, and other CAMSS
> blocks.
>
> Introduce a small PM clock descriptor table in the CAMSS resources
> structure to describe clocks and their optional rates. Initialize
> these clocks at probe time and delegate clock ownership to the PM
> core.
>
> Hook PM clock handling into the runtime PM callbacks to ensure clocks
> are properly suspended and resumed alongside power domains and ICC
> paths.
>
> Reviewed-by: Bryan O'Donoghue <[email protected]>
> Reviewed-by: Frank Li <[email protected]>
> Signed-off-by: Loic Poulain <[email protected]>
> Signed-off-by: Bryan O'Donoghue <[email protected]>
Patch committed.
Thanks,
Bryan O'Donoghue
drivers/media/platform/qcom/camss/camss.c | 49 +++++++++++++++++++++++++++++++
drivers/media/platform/qcom/camss/camss.h | 1 +
2 files changed, 50 insertions(+)
---
diff --git a/drivers/media/platform/qcom/camss/camss.c
b/drivers/media/platform/qcom/camss/camss.c
index e4d0128a3d19..d1969a7fda13 100644
--- a/drivers/media/platform/qcom/camss/camss.c
+++ b/drivers/media/platform/qcom/camss/camss.c
@@ -18,6 +18,7 @@
#include <linux/of_graph.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
+#include <linux/pm_clock.h>
#include <linux/slab.h>
#include <linux/videodev2.h>
@@ -5344,6 +5345,40 @@ static void camss_genpd_cleanup(struct camss *camss)
dev_pm_domain_detach(camss->genpd, true);
}
+/*
+ * camss_init_pm_clks - set up shared CAMSS clocks
+ *
+ * Clocks listed in res->pm_clks are shared across all CAMSS sub-devices
+ * (e.g. top_ahb, axi).
+ */
+static int camss_init_pm_clks(struct camss *camss)
+{
+ struct device *dev = camss->dev;
+ unsigned int i;
+ int ret;
+
+ if (!camss->res->pm_clks[0])
+ return 0;
+
+ if (IS_ENABLED(CONFIG_PM_CLK)) {
+ ret = devm_pm_clk_create(dev);
+ if (ret)
+ return ret;
+ }
+
+ for (i = 0; i < CAMSS_RES_MAX && camss->res->pm_clks[i]; i++) {
+ if (IS_ENABLED(CONFIG_PM_CLK))
+ ret = pm_clk_add(dev, camss->res->pm_clks[i]);
+ else
+ ret = PTR_ERR_OR_ZERO(devm_clk_get_enabled(dev,
camss->res->pm_clks[i]));
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to set up pm
clock %s\n",
+ camss->res->pm_clks[i]);
+ }
+
+ return 0;
+}
+
/*
* camss_probe - Probe CAMSS platform device
* @pdev: Pointer to CAMSS platform device
@@ -5432,6 +5467,10 @@ static int camss_probe(struct platform_device *pdev)
pm_runtime_enable(dev);
+ ret = camss_init_pm_clks(camss);
+ if (ret)
+ goto err_v4l2_device_unregister;
+
ret = camss_parse_ports(camss);
if (ret < 0)
goto err_v4l2_device_unregister;
@@ -5773,7 +5812,11 @@ static int __maybe_unused camss_runtime_suspend(struct
device *dev)
return ret;
}
+#if IS_ENABLED(CONFIG_PM_CLK)
+ return pm_clk_suspend(dev);
+#else
return 0;
+#endif
}
static int __maybe_unused camss_runtime_resume(struct device *dev)
@@ -5783,6 +5826,12 @@ static int __maybe_unused camss_runtime_resume(struct
device *dev)
int i;
int ret;
+#if IS_ENABLED(CONFIG_PM_CLK)
+ ret = pm_clk_resume(dev);
+ if (ret)
+ return ret;
+#endif
+
for (i = 0; i < camss->res->icc_path_num; i++) {
ret = icc_set_bw(camss->icc_path[i],
icc_res[i].icc_bw_tbl.avg,
diff --git a/drivers/media/platform/qcom/camss/camss.h
b/drivers/media/platform/qcom/camss/camss.h
index 93d691c8ac63..fe5fe25d5f18 100644
--- a/drivers/media/platform/qcom/camss/camss.h
+++ b/drivers/media/platform/qcom/camss/camss.h
@@ -107,6 +107,7 @@ enum icc_count {
struct camss_resources {
enum camss_version version;
const char *pd_name;
+ const char *pm_clks[CAMSS_RES_MAX];
const struct camss_subdev_resources *csiphy_res;
const struct camss_subdev_resources *tpg_res;
const struct camss_subdev_resources *csid_res;
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