media: qcom: camss: Add support for named power-domains

Right now we use fixed indexes to assign power-domains, with a
requirement for the TOP GDSC to come last in the list.

Adding support for named power-domains means the declaration in the dtsi
can come in any order.

After this change we continue to support the old indexing - if a SoC
resource declaration or the in-use dtb doesn't declare power-domain names
we fall back to the default legacy indexing.

From this point on though new SoC additions should contain named
power-domains, eventually we will drop support for legacy indexing.
Tested-by: Matti Lehtimäki <matti.lehtimaki@gmail.com>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/platform/qcom/camss/camss-vfe.c

@@ -1380,7 +1380,29 @@ int msm_vfe_subdev_init(struct camss *camss, struct vfe_device *vfe,
 	if (!res->line_num)
 		return -EINVAL;
 
-	if (res->has_pd) {
+	/* Power domain */
+
+	if (res->pd_name) {
+		vfe->genpd = dev_pm_domain_attach_by_name(camss->dev,
+							  res->pd_name);
+		if (IS_ERR(vfe->genpd)) {
+			ret = PTR_ERR(vfe->genpd);
+			return ret;
+		}
+	}
+
+	if (!vfe->genpd && res->has_pd) {
+		/*
+		 * Legacy magic index.
+		 * Requires
+		 * power-domain = <VFE_X>,
+		 *                <VFE_Y>,
+		 *                <TITAN_TOP>
+		 * id must correspondng to the index of the VFE which must
+		 * come before the TOP GDSC. VFE Lite has no individually
+		 * collapasible domain which is why id < vfe_num is a valid
+		 * check.
+		 */
 		vfe->genpd = dev_pm_domain_attach_by_id(camss->dev, id);
 		if (IS_ERR(vfe->genpd))
 			return PTR_ERR(vfe->genpd);

drivers/media/platform/qcom/camss/camss.c

@@ -1522,13 +1522,32 @@ static int camss_configure_pd(struct camss *camss)
 		return 0;
 
 	/*
-	 * VFE power domains are in the beginning of the list, and while all
-	 * power domains should be attached, only if TITAN_TOP power domain is
-	 * found in the list, it should be linked over here.
+	 * If a power-domain name is defined try to use it.
+	 * It is possible we are running a new kernel with an old dtb so
+	 * fallback to indexes even if a pd_name is defined but not found.
 	 */
-	camss->genpd = dev_pm_domain_attach_by_id(camss->dev, camss->genpd_num - 1);
-	if (IS_ERR(camss->genpd)) {
-		ret = PTR_ERR(camss->genpd);
+	if (camss->res->pd_name) {
+		camss->genpd = dev_pm_domain_attach_by_name(camss->dev,
+							    camss->res->pd_name);
+		if (IS_ERR(camss->genpd)) {
+			ret = PTR_ERR(camss->genpd);
+			goto fail_pm;
+		}
+	}
+
+	if (!camss->genpd) {
+		/*
+		 * Legacy magic index. TITAN_TOP GDSC must be the last
+		 * item in the power-domain list.
+		 */
+		camss->genpd = dev_pm_domain_attach_by_id(camss->dev,
+							  camss->genpd_num - 1);
+	}
+	if (IS_ERR_OR_NULL(camss->genpd)) {
+		if (!camss->genpd)
+			ret = -ENODEV;
+		else
+			ret = PTR_ERR(camss->genpd);
 		goto fail_pm;
 	}
 	camss->genpd_link = device_link_add(camss->dev, camss->genpd,

drivers/media/platform/qcom/camss/camss.h

@@ -48,6 +48,7 @@ struct camss_subdev_resources {
 	u32 clock_rate[CAMSS_RES_MAX][CAMSS_RES_MAX];
 	char *reg[CAMSS_RES_MAX];
 	char *interrupt[CAMSS_RES_MAX];
+	char *pd_name;
 	u8 line_num;
 	bool has_pd;
 	const void *ops;
@@ -84,6 +85,7 @@ enum icc_count {
 
 struct camss_resources {
 	enum camss_version version;
+	const char *pd_name;
 	const struct camss_subdev_resources *csiphy_res;
 	const struct camss_subdev_resources *csid_res;
 	const struct camss_subdev_resources *ispif_res;