linux-kernel - [PATCH] drm/panfrost: increase readl_relaxed_poll

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Date:   Thu,  8 Oct 2020 14:17:38 +0000
From:   Christian Hewitt <christianshewitt@...il.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Christian Hewitt <christianshewitt@...il.com>
Subject: [PATCH] drm/panfrost: increase readl_relaxed_poll_timeout values

Amlogic SoC devices report the following errors frequently causing excessive
dmesg log spam and early log rotataion, although the errors appear to be
harmless as everything works fine:

[    7.202702] panfrost ffe40000.gpu: error powering up gpu L2
[    7.203760] panfrost ffe40000.gpu: error powering up gpu shader

ARM staff have advised increasing the timeout values to eliminate the errors
in most normal scenarios, and testing with several different G31/G52 devices
shows 20000 to be a reliable value.

Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
Suggested-by: Steven Price <steven.price@....com>
Signed-off-by: Christian Hewitt <christianshewitt@...il.com>
---
 drivers/gpu/drm/panfrost/panfrost_gpu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index e1b2a3376624..2aae636f1cf5 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -325,13 +325,13 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 	/* Just turn on everything for now */
 	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
-		val, val == pfdev->features.l2_present, 100, 1000);
+		val, val == pfdev->features.l2_present, 100, 20000);
 	if (ret)
 		dev_err(pfdev->dev, "error powering up gpu L2");
 
 	gpu_write(pfdev, SHADER_PWRON_LO, pfdev->features.shader_present);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
-		val, val == pfdev->features.shader_present, 100, 1000);
+		val, val == pfdev->features.shader_present, 100, 20000);
 	if (ret)
 		dev_err(pfdev->dev, "error powering up gpu shader");
 
-- 
2.17.1