[PATCH v3 4/6] media: qcom: camss: share VFE clock sources by the highest rate

[Atanas Filipov]

Clocks of different VFEs can be fed by one clock source, and each VFE
sets such a source to the rate it needs. A VFE started later at a lower
rate then lowers the source under a VFE that is still running.

For example, on SM8250 the two VFE Lite share one core clock source,
which the VFE sets to 400 or 480 MHz from the pixel rate. With VFE Lite
0 streaming the CSID test pattern at 480 MHz, starting an imx577 stream
on VFE Lite 1 sets the shared source to 400 MHz under the running VFE
Lite 0.

Request the VFE clock rates as minimums with clk_set_rate_range(), so
that a shared clock runs at the highest minimum of its running VFEs.
On power off the VFE drops its minimum and sets the clock to its lowest
listed rate within the remaining minimums.

Rate ranges are enabled through the vfe_clock_ranges resource flag, so
far only on SM8250.

Signed-off-by: Atanas Filipov <atanas.filipov@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/camss/camss-vfe.c | 45 +++++++++++++++++--
 drivers/media/platform/qcom/camss/camss.c     |  1 +
 drivers/media/platform/qcom/camss/camss.h     |  1 +
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe.c b/drivers/media/platform/qcom/camss/camss-vfe.c
index 359b5942df89..30504e614e4b 100644
--- a/drivers/media/platform/qcom/camss/camss-vfe.c
+++ b/drivers/media/platform/qcom/camss/camss-vfe.c
@@ -1016,7 +1016,10 @@ static int vfe_set_clock_rates(struct vfe_device *vfe)
 				return -EINVAL;
 			}
 
-			ret = clk_set_rate(clock->clk, rate);
+			if (vfe->camss->res->vfe_clock_ranges)
+				ret = clk_set_rate_range(clock->clk, clock->freq[j], ULONG_MAX);
+			else
+				ret = clk_set_rate(clock->clk, rate);
 			if (ret < 0) {
 				dev_err(dev, "clk set rate failed: %d\n", ret);
 				return ret;
@@ -1060,6 +1063,37 @@ static int vfe_check_clock_rates(struct vfe_device *vfe)
 	return 0;
 }
 
+/*
+ * vfe_release_clock_rates - Release the minimum clock rates of VFE module
+ * @vfe: VFE device
+ *
+ * Drop the minimum rate requested by the VFE from each of its clocks and set
+ * the clock to its lowest level, or to the highest minimum rate still
+ * requested by the other users of the clock.
+ */
+static void vfe_release_clock_rates(struct vfe_device *vfe)
+{
+	int i;
+
+	if (!vfe->camss->res->vfe_clock_ranges)
+		return;
+
+	for (i = 0; i < vfe->nclocks; i++) {
+		struct camss_clock *clock = &vfe->clock[i];
+		long rate;
+
+		if (!vfe_match_clock_names(vfe, clock) || !vfe_check_clock_levels(clock))
+			continue;
+
+		clk_drop_range(clock->clk);
+
+		/* Round first, so that the rate respects the other users' ranges */
+		rate = clk_round_rate(clock->clk, clock->freq[0]);
+		if (rate > 0)
+			clk_set_rate(clock->clk, rate);
+	}
+}
+
 /*
  * vfe_get - Power up and reset VFE module
  * @vfe: VFE Device
@@ -1083,12 +1117,12 @@ int vfe_get(struct vfe_device *vfe)
 
 		ret = vfe_set_clock_rates(vfe);
 		if (ret < 0)
-			goto error_pm_runtime_get;
+			goto error_release_rates;
 
 		ret = camss_enable_clocks(vfe->nclocks, vfe->clock,
 					  vfe->camss->dev);
 		if (ret < 0)
-			goto error_pm_runtime_get;
+			goto error_release_rates;
 
 		ret = vfe_reset(vfe);
 		if (ret < 0)
@@ -1113,7 +1147,9 @@ int vfe_get(struct vfe_device *vfe)
 error_reset:
 	camss_disable_clocks(vfe->nclocks, vfe->clock);
 
-error_pm_runtime_get:
+error_release_rates:
+	vfe_release_clock_rates(vfe);
+
 	pm_runtime_put_sync(vfe->camss->dev);
 error_domain_off:
 	vfe->res->hw_ops->pm_domain_off(vfe);
@@ -1141,6 +1177,7 @@ void vfe_put(struct vfe_device *vfe)
 			vfe->res->hw_ops->vfe_halt(vfe);
 		}
 		camss_disable_clocks(vfe->nclocks, vfe->clock);
+		vfe_release_clock_rates(vfe);
 		pm_runtime_put_sync(vfe->camss->dev);
 		vfe->res->hw_ops->pm_domain_off(vfe);
 	}
diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c
index 7fe12049b78a..80eab898611d 100644
--- a/drivers/media/platform/qcom/camss/camss.c
+++ b/drivers/media/platform/qcom/camss/camss.c
@@ -5736,6 +5736,7 @@ static const struct camss_resources sm8250_resources = {
 	.csiphy_num = ARRAY_SIZE(csiphy_res_8250),
 	.csid_num = ARRAY_SIZE(csid_res_8250),
 	.vfe_num = ARRAY_SIZE(vfe_res_8250),
+	.vfe_clock_ranges = true,
 };
 
 static const struct camss_resources sc8280xp_resources = {
diff --git a/drivers/media/platform/qcom/camss/camss.h b/drivers/media/platform/qcom/camss/camss.h
index 7dc2fd9f03e0..bffff5b6bfbe 100644
--- a/drivers/media/platform/qcom/camss/camss.h
+++ b/drivers/media/platform/qcom/camss/camss.h
@@ -120,6 +120,7 @@ struct camss_resources {
 	const unsigned int tpg_num;
 	const unsigned int csid_num;
 	const unsigned int vfe_num;
+	const bool vfe_clock_ranges;
 };
 
 struct camss {
-- 
2.34.1