[RFC PATCH 2/3] drm/msm/a5xx: scale MX domain following the frequncy changes

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

For some a5xx Adrenos we have to specify both GX and MX power domains.
GX is used to power up the GPU clocks and logic. MX is used for scaling
voltage of memory cells.

In case the DT specifies several (GX, MX) power domains, none will be
bound by the core. We have to manage GX manually. Also make sure that
the MX domain is resumed and scaled to the proper performance state
following the desired frequency.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 52 +++++++++++++++++++++++++++
 drivers/gpu/drm/msm/adreno/a5xx_gpu.h |  3 ++
 2 files changed, 55 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index 0372f8908202..36b3d11dd5b0 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -8,6 +8,7 @@
 #include <linux/firmware/qcom/qcom_scm.h>
 #include <linux/pm_opp.h>
 #include <linux/nvmem-consumer.h>
+#include <linux/pm_domain.h>
 #include <linux/slab.h>
 #include "msm_gem.h"
 #include "msm_mmu.h"
@@ -1053,6 +1054,13 @@ static void a5xx_destroy(struct msm_gpu *gpu)
 	}
 
 	adreno_gpu_cleanup(adreno_gpu);
+
+	if (a5xx_gpu->mx_link)
+		device_link_del(a5xx_gpu->mx_link);
+
+	if (a5xx_gpu->gxpd)
+		dev_pm_domain_detach(a5xx_gpu->gxpd, true);
+
 	kfree(a5xx_gpu);
 }
 
@@ -1339,8 +1347,15 @@ static void a5xx_dump(struct msm_gpu *gpu)
 static int a5xx_pm_resume(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
 	int ret;
 
+	if (a5xx_gpu->gxpd) {
+		ret = pm_runtime_resume_and_get(a5xx_gpu->gxpd);
+		if (ret < 0)
+			return ret;
+	}
+
 	/* Turn on the core power */
 	ret = msm_gpu_pm_resume(gpu);
 	if (ret)
@@ -1414,6 +1429,9 @@ static int a5xx_pm_suspend(struct msm_gpu *gpu)
 	if (ret)
 		return ret;
 
+	if (a5xx_gpu->gxpd)
+		pm_runtime_put(a5xx_gpu->gxpd);
+
 	if (a5xx_gpu->has_whereami)
 		for (i = 0; i < gpu->nr_rings; i++)
 			a5xx_gpu->shadow[i] = 0;
@@ -1762,6 +1780,40 @@ struct msm_gpu *a5xx_gpu_init(struct drm_device *dev)
 
 	a5xx_gpu->lm_leakage = 0x4E001A;
 
+	/*
+	 * If the device has several power domain (gx and mx), none are attached by the core.
+	 */
+	if (!pdev->dev.pm_domain) {
+		struct device **opp_virt_dev;
+		struct device *pd;
+
+		/* FIXME: add cpr once it is supported */
+		static const char *genpd_names[] = { "mx", NULL };
+
+		pd = dev_pm_domain_attach_by_name(&pdev->dev, "gx");
+		if (IS_ERR(pd))
+			return ERR_CAST(pd);
+
+		/* GX is required for GPU to function */
+		if (pd == NULL)
+			return ERR_PTR(-EINVAL);
+
+		a5xx_gpu->gxpd = pd;
+
+		ret = devm_pm_opp_attach_genpd(&pdev->dev, genpd_names, &opp_virt_dev);
+		if (ret) {
+			dev_pm_domain_detach(a5xx_gpu->gxpd, true);
+			return ERR_PTR(ret);
+		}
+
+		a5xx_gpu->mx_link = device_link_add(&pdev->dev, opp_virt_dev[0],
+						    DL_FLAG_RPM_ACTIVE |
+						    DL_FLAG_PM_RUNTIME |
+						    DL_FLAG_STATELESS);
+		if (!a5xx_gpu->mx_link)
+			return ERR_PTR(-ENODEV);
+	}
+
 	check_speed_bin(&pdev->dev);
 
 	nr_rings = 4;
diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.h b/drivers/gpu/drm/msm/adreno/a5xx_gpu.h
index c7187bcc5e90..36e910397c14 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.h
@@ -44,6 +44,9 @@ struct a5xx_gpu {
 
 	/* True if the microcode supports the WHERE_AM_I opcode */
 	bool has_whereami;
+
+	struct device *gxpd;
+	struct device_link *mx_link;
 };
 
 #define to_a5xx_gpu(x) container_of(x, struct a5xx_gpu, base)
-- 
2.39.2