drm/msm/gpu: Add devfreq tuning debugfs

Make the handful of tuning knobs available visible via debugfs.

v2: select DEVFREQ_GOV_SIMPLE_ONDEMAND because for some reason
    struct devfreq_simple_ondemand_data depends on this

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/517784/
Link: https://lore.kernel.org/r/20230110231447.1939101-2-robdclark@gmail.com
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>

drivers/gpu/drm/msm/Kconfig

@@ -23,6 +23,7 @@ config DRM_MSM
 	select SHMEM
 	select TMPFS
 	select QCOM_SCM
+	select DEVFREQ_GOV_SIMPLE_ONDEMAND
 	select WANT_DEV_COREDUMP
 	select SND_SOC_HDMI_CODEC if SND_SOC
 	select SYNC_FILE

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -2021,7 +2021,7 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 	 * to cause power supply issues:
 	 */
 	if (adreno_is_a618(adreno_gpu) || adreno_is_7c3(adreno_gpu))
-		gpu->clamp_to_idle = true;
+		priv->gpu_clamp_to_idle = true;
 
 	/* Check if there is a GMU phandle and set it up */
 	node = of_parse_phandle(pdev->dev.of_node, "qcom,gmu", 0);

drivers/gpu/drm/msm/msm_debugfs.c

@@ -305,6 +305,7 @@ void msm_debugfs_init(struct drm_minor *minor)
 {
 	struct drm_device *dev = minor->dev;
 	struct msm_drm_private *priv = dev->dev_private;
+	struct dentry *gpu_devfreq;
 
 	drm_debugfs_create_files(msm_debugfs_list,
 				 ARRAY_SIZE(msm_debugfs_list),
@@ -325,6 +326,17 @@ void msm_debugfs_init(struct drm_minor *minor)
 	debugfs_create_file("shrink", S_IRWXU, minor->debugfs_root,
 		dev, &shrink_fops);
 
+	gpu_devfreq = debugfs_create_dir("devfreq", minor->debugfs_root);
+
+	debugfs_create_bool("idle_clamp",0600, gpu_devfreq,
+			    &priv->gpu_clamp_to_idle);
+
+	debugfs_create_u32("upthreshold",0600, gpu_devfreq,
+			   &priv->gpu_devfreq_config.upthreshold);
+
+	debugfs_create_u32("downdifferential",0600, gpu_devfreq,
+			   &priv->gpu_devfreq_config.downdifferential);
+
 	if (priv->kms && priv->kms->funcs->debugfs_init)
 		priv->kms->funcs->debugfs_init(priv->kms, minor);
 

drivers/gpu/drm/msm/msm_drv.h

@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/clk.h>
 #include <linux/cpufreq.h>
+#include <linux/devfreq.h>
 #include <linux/module.h>
 #include <linux/component.h>
 #include <linux/platform_device.h>
@@ -233,6 +234,14 @@ struct msm_drm_private {
 	 */
 	unsigned int hangcheck_period;
 
+	/** gpu_devfreq_config: Devfreq tuning config for the GPU. */
+	struct devfreq_simple_ondemand_data gpu_devfreq_config;
+
+	/**
+	 * gpu_clamp_to_idle: Enable clamping to idle freq when inactive
+	 */
+	bool gpu_clamp_to_idle;
+
 	/**
 	 * disable_err_irq:
 	 *

drivers/gpu/drm/msm/msm_gpu.h

@@ -275,9 +275,6 @@ struct msm_gpu {
 
 	struct msm_gpu_state *crashstate;
 
-	/* Enable clamping to idle freq when inactive: */
-	bool clamp_to_idle;
-
 	/* True if the hardware supports expanded apriv (a650 and newer) */
 	bool hw_apriv;
 

drivers/gpu/drm/msm/msm_gpu_devfreq.c

@@ -183,6 +183,7 @@ static bool has_devfreq(struct msm_gpu *gpu)
 void msm_devfreq_init(struct msm_gpu *gpu)
 {
 	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	struct msm_drm_private *priv = gpu->dev->dev_private;
 
 	/* We need target support to do devfreq */
 	if (!gpu->funcs->gpu_busy)
@@ -209,7 +210,7 @@ void msm_devfreq_init(struct msm_gpu *gpu)
 
 	df->devfreq = devm_devfreq_add_device(&gpu->pdev->dev,
 			&msm_devfreq_profile, DEVFREQ_GOV_SIMPLE_ONDEMAND,
-			NULL);
+			&priv->gpu_devfreq_config);
 
 	if (IS_ERR(df->devfreq)) {
 		DRM_DEV_ERROR(&gpu->pdev->dev, "Couldn't initialize GPU devfreq\n");
@@ -358,10 +359,11 @@ static void msm_devfreq_idle_work(struct kthread_work *work)
 	struct msm_gpu_devfreq *df = container_of(work,
 			struct msm_gpu_devfreq, idle_work.work);
 	struct msm_gpu *gpu = container_of(df, struct msm_gpu, devfreq);
+	struct msm_drm_private *priv = gpu->dev->dev_private;
 
 	df->idle_time = ktime_get();
 
-	if (gpu->clamp_to_idle)
+	if (priv->gpu_clamp_to_idle)
 		dev_pm_qos_update_request(&df->idle_freq, 0);
 }