linux-kernel - [PATCH] drm/msm/devfreq: Restrict idle clamping to a618 for now

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Message-Id: <20211018153627.2787882-1-robdclark@gmail.com>
Date:   Mon, 18 Oct 2021 08:36:25 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Caleb Connolly <caleb.connolly@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Sharat Masetty <smasetty@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] drm/msm/devfreq: Restrict idle clamping to a618 for now

From: Rob Clark <robdclark@...omium.org>

Until we better understand the stability issues caused by frequent
frequency changes, lets limit them to a618.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
Caleb/John, I think this should help as a workaround for the power
instability issues on a630.. could you give it a try?

 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 7 +++++++
 drivers/gpu/drm/msm/msm_gpu.h         | 4 ++++
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 3 ++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 33da25b81615..267a880811d6 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1838,6 +1838,13 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 			adreno_cmp_rev(ADRENO_REV(6, 3, 5, ANY_ID), info->rev)))
 		adreno_gpu->base.hw_apriv = true;
 
+	/*
+	 * For now only clamp to idle freq for devices where this is known not
+	 * to cause power supply issues:
+	 */
+	if (info && (info->revn == 618))
+		gpu->clamp_to_idle = true;
+
 	a6xx_llc_slices_init(pdev, a6xx_gpu);
 
 	ret = a6xx_set_supported_hw(&pdev->dev, config->rev);
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 59870095ea41..59cdd00b69d0 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -210,6 +210,10 @@ struct msm_gpu {
 	uint32_t suspend_count;
 
 	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;
 
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index d32b729b4616..8b7473f69cb8 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -214,7 +214,8 @@ static void msm_devfreq_idle_work(struct kthread_work *work)
 
 	idle_freq = get_freq(gpu);
 
-	msm_devfreq_target(&gpu->pdev->dev, &target_freq, 0);
+	if (gpu->clamp_to_idle)
+		msm_devfreq_target(&gpu->pdev->dev, &target_freq, 0);
 
 	df->idle_time = ktime_get();
 	df->idle_freq = idle_freq;
-- 
2.31.1