drm/msm/adreno: Use OPP for every GPU generation

Some older GPUs (namely a2xx with no opp tables at all and a320 with
downstream-remnants gpu pwrlevels) used not to have OPP tables. They
both however had just one frequency defined, making it extremely easy
to construct such an OPP table from within the driver if need be.

Do so and switch all clk_set_rate calls on core_clk to their OPP
counterparts.
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/523784/
Link: https://lore.kernel.org/r/20230223-topic-opp-v3-3-5f22163cd1df@linaro.orgSigned-off-by: Rob Clark <robdclark@chromium.org>

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

@@ -922,73 +922,46 @@ void adreno_wait_ring(struct msm_ringbuffer *ring, uint32_t ndwords)
 			ring->id);
 }
 
-/* Get legacy powerlevels from qcom,gpu-pwrlevels and populate the opp table */
-static int adreno_get_legacy_pwrlevels(struct device *dev)
-{
-	struct device_node *child, *node;
-	int ret;
-
-	node = of_get_compatible_child(dev->of_node, "qcom,gpu-pwrlevels");
-	if (!node) {
-		DRM_DEV_DEBUG(dev, "Could not find the GPU powerlevels\n");
-		return -ENXIO;
-	}
-
-	for_each_child_of_node(node, child) {
-		unsigned int val;
-
-		ret = of_property_read_u32(child, "qcom,gpu-freq", &val);
-		if (ret)
-			continue;
-
-		/*
-		 * Skip the intentionally bogus clock value found at the bottom
-		 * of most legacy frequency tables
-		 */
-		if (val != 27000000)
-			dev_pm_opp_add(dev, val, 0);
-	}
-
-	of_node_put(node);
-
-	return 0;
-}
-
-static void adreno_get_pwrlevels(struct device *dev,
+static int adreno_get_pwrlevels(struct device *dev,
 		struct msm_gpu *gpu)
 {
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	unsigned long freq = ULONG_MAX;
 	struct dev_pm_opp *opp;
 	int ret;
 
 	gpu->fast_rate = 0;
 
-	/* You down with OPP? */
-	if (!of_find_property(dev->of_node, "operating-points-v2", NULL))
-		ret = adreno_get_legacy_pwrlevels(dev);
-	else {
+	/* devm_pm_opp_of_add_table may error out but will still create an OPP table */
 	ret = devm_pm_opp_of_add_table(dev);
-		if (ret)
+	if (ret == -ENODEV) {
+		/* Special cases for ancient hw with ancient DT bindings */
+		if (adreno_is_a2xx(adreno_gpu)) {
+			dev_warn(dev, "Unable to find the OPP table. Falling back to 200 MHz.\n");
+			dev_pm_opp_add(dev, 200000000, 0);
+		} else if (adreno_is_a320(adreno_gpu)) {
+			dev_warn(dev, "Unable to find the OPP table. Falling back to 450 MHz.\n");
+			dev_pm_opp_add(dev, 450000000, 0);
+		} else {
+			DRM_DEV_ERROR(dev, "Unable to find the OPP table\n");
+			return -ENODEV;
+		}
+	} else if (ret) {
 		DRM_DEV_ERROR(dev, "Unable to set the OPP table\n");
+		return ret;
 	}
 
-	if (!ret) {
 	/* Find the fastest defined rate */
 	opp = dev_pm_opp_find_freq_floor(dev, &freq);
-		if (!IS_ERR(opp)) {
+	if (IS_ERR(opp))
+		return PTR_ERR(opp);
+
 	gpu->fast_rate = freq;
 	dev_pm_opp_put(opp);
-		}
-	}
-
-	if (!gpu->fast_rate) {
-		dev_warn(dev,
-			"Could not find a clock rate. Using a reasonable default\n");
-		/* Pick a suitably safe clock speed for any target */
-		gpu->fast_rate = 200000000;
-	}
 
 	DBG("fast_rate=%u, slow_rate=27000000", gpu->fast_rate);
+
+	return 0;
 }
 
 int adreno_gpu_ocmem_init(struct device *dev, struct adreno_gpu *adreno_gpu,
@@ -1046,6 +1019,20 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
 	struct adreno_rev *rev = &config->rev;
 	const char *gpu_name;
 	u32 speedbin;
+	int ret;
+
+	/*
+	 * This can only be done before devm_pm_opp_of_add_table(), or
+	 * dev_pm_opp_set_config() will WARN_ON()
+	 */
+	if (IS_ERR(devm_clk_get(dev, "core"))) {
+		/*
+		 * If "core" is absent, go for the legacy clock name.
+		 * If we got this far in probing, it's a given one of them exists.
+		 */
+		devm_pm_opp_set_clkname(dev, "core_clk");
+	} else
+		devm_pm_opp_set_clkname(dev, "core");
 
 	adreno_gpu->funcs = funcs;
 	adreno_gpu->info = adreno_info(config->rev);
@@ -1070,7 +1057,9 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
 
 	adreno_gpu_config.nr_rings = nr_rings;
 
-	adreno_get_pwrlevels(dev, gpu);
+	ret = adreno_get_pwrlevels(dev, gpu);
+	if (ret)
+		return ret;
 
 	pm_runtime_set_autosuspend_delay(dev,
 		adreno_gpu->info->inactive_period);

drivers/gpu/drm/msm/msm_gpu.c

@@ -58,7 +58,7 @@ static int disable_pwrrail(struct msm_gpu *gpu)
 static int enable_clk(struct msm_gpu *gpu)
 {
 	if (gpu->core_clk && gpu->fast_rate)
-		clk_set_rate(gpu->core_clk, gpu->fast_rate);
+		dev_pm_opp_set_rate(&gpu->pdev->dev, gpu->fast_rate);
 
 	/* Set the RBBM timer rate to 19.2Mhz */
 	if (gpu->rbbmtimer_clk)
@@ -77,7 +77,7 @@ static int disable_clk(struct msm_gpu *gpu)
 	 * will be rounded down to zero anyway so it all works out.
 	 */
 	if (gpu->core_clk)
-		clk_set_rate(gpu->core_clk, 27000000);
+		dev_pm_opp_set_rate(&gpu->pdev->dev, 27000000);
 
 	if (gpu->rbbmtimer_clk)
 		clk_set_rate(gpu->rbbmtimer_clk, 0);

drivers/gpu/drm/msm/msm_gpu_devfreq.c

@@ -48,7 +48,7 @@ static int msm_devfreq_target(struct device *dev, unsigned long *freq,
 		gpu->funcs->gpu_set_freq(gpu, opp, df->suspended);
 		mutex_unlock(&df->lock);
 	} else {
-		clk_set_rate(gpu->core_clk, *freq);
+		dev_pm_opp_set_rate(dev, *freq);
 	}
 
 	dev_pm_opp_put(opp);