0003-HACK-drm-vc4-Keep-the-VEC-clock-running-all-the-time.patch

From 694299489e9a1e7b95245c4adff272b980f7f852 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Fri, 2 Sep 2022 13:19:15 +0200
Subject: [PATCH 3/3] HACK: drm/vc4: Keep the VEC clock running all the time
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Workaround to prevent crash on Pi4 when running command:

$ modetest -M vc4 -s 45:720x576i -w 45:'TV mode':4

Crash report:

[  166.702171] SError Interrupt on CPU1, code 0x00000000bf000002 -- SError
[  166.702187] CPU: 1 PID: 8 Comm: kworker/u8:0 Tainted: G        W         5.19.0-rc6-00096-gba7973977976-dirty #1
[  166.702200] Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
[  166.702206] Workqueue: events_freezable_power_ thermal_zone_device_check
[  166.702231] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  166.702242] pc : regmap_mmio_read32le+0x10/0x28
[  166.702261] lr : regmap_mmio_read+0x44/0x70
[  166.702271] sp : ffff800008063bf0
[  166.702274] x29: ffff800008063bf0 x28: ffffba2ec3257000 x27: ffff22e50000c078
[  166.702290] x26: ffff22e50000c028 x25: 0000000000000000 x24: ffff22e500831be0
[  166.702303] x23: ffff800008063da4 x22: ffff800008063cc4 x21: ffff800008063cc4
[  166.702315] x20: 0000000000000200 x19: ffff22e503c9ae00 x18: 0000000000000010
[  166.702328] x17: 0000000400000000 x16: ffffba2ec2528798 x15: 000000532dba6262
[  166.702341] x14: 0000000000000094 x13: 0000000000000001 x12: 0000000000000000
[  166.702354] x11: 0000000000000001 x10: 0000000000000a50 x9 : ffff22e500041584
[  166.702366] x8 : fefefefefefefeff x7 : 0000000000000018 x6 : ffff22e500041574
[  166.702378] x5 : 005f7265776f705f x4 : 0000000000000000 x3 : ffffba2ec252ea68
[  166.702390] x2 : ffffba2ec252e8b0 x1 : 0000000000000200 x0 : 0000000000000000
[  166.702405] Kernel panic - not syncing: Asynchronous SError Interrupt
[  166.702410] CPU: 1 PID: 8 Comm: kworker/u8:0 Tainted: G        W         5.19.0-rc6-00096-gba7973977976-dirty #1
[  166.702421] Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
[  166.702425] Workqueue: events_freezable_power_ thermal_zone_device_check
[  166.702439] Call trace:
[  166.702443]  dump_backtrace+0xdc/0xe8
[  166.702463]  show_stack+0x18/0x68
[  166.702475]  dump_stack_lvl+0x68/0x84
[  166.702488]  dump_stack+0x18/0x34
[  166.702496]  panic+0x16c/0x32c
[  166.702513]  add_taint+0x0/0xa8
[  166.702526]  arm64_serror_panic+0x6c/0x80
[  166.702534]  do_serror+0x34/0x80
[  166.702541]  el1h_64_error_handler+0x34/0x50
[  166.702555]  el1h_64_error+0x64/0x68
[  166.702563]  regmap_mmio_read32le+0x10/0x28
[  166.702573]  _regmap_bus_reg_read+0x18/0x28
[  166.702591]  _regmap_read+0x64/0xf8
[  166.702598]  regmap_read+0x4c/0x78
[  166.702606]  bcm2711_get_temp+0x58/0xb0 [bcm2711_thermal]
[  166.702622]  of_thermal_get_temp+0x28/0x40
[  166.702637]  thermal_zone_get_temp+0x70/0x158
[  166.702648]  thermal_zone_device_update+0x7c/0x2d8
[  166.702658]  thermal_zone_device_check+0x18/0x28
[  166.702668]  process_one_work+0x1c0/0x308
[  166.702681]  worker_thread+0x4c/0x400
[  166.702691]  kthread+0x110/0x120
[  166.702699]  ret_from_fork+0x10/0x20
[  166.702710] SMP: stopping secondary CPUs
[  167.834381] SMP: failed to stop secondary CPUs 0-2
[  167.834389] Kernel Offset: 0x3a2eb9e00000 from 0xffff800008000000
[  167.834395] PHYS_OFFSET: 0xffffdd1b40000000
[  167.834398] CPU features: 0x800,00027810,00001086
[  167.834404] Memory Limit: none
[  168.135055] ---[ end Kernel panic - not syncing: Asynchronous SError Interrupt ]---

Link: https://lore.kernel.org/dri-devel/24e09a29-6d04-3b1e-63ce-cd3c31d350e2@tronnes.org/T/#u

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/vc4/vc4_vec.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_vec.c b/drivers/gpu/drm/vc4/vc4_vec.c
index 55f6f490877c..7191bce270b0 100644
--- a/drivers/gpu/drm/vc4/vc4_vec.c
+++ b/drivers/gpu/drm/vc4/vc4_vec.c
@@ -543,8 +543,6 @@ static void vc4_vec_encoder_disable(struct drm_encoder *encoder,
 		  VEC_DAC_MISC_DAC_PWRDN |
 		  VEC_DAC_MISC_LDO_PWRDN);
 
-	clk_disable_unprepare(vec->clock);
-
 	ret = pm_runtime_put(&vec->pdev->dev);
 	if (ret < 0) {
 		DRM_ERROR("Failed to release power domain: %d\n", ret);
@@ -595,12 +593,6 @@ static void vc4_vec_encoder_enable(struct drm_encoder *encoder,
 		goto err_put_runtime_pm;
 	}
 
-	ret = clk_prepare_enable(vec->clock);
-	if (ret) {
-		DRM_ERROR("Failed to turn on core clock: %d\n", ret);
-		goto err_put_runtime_pm;
-	}
-
 	/* Reset the different blocks */
 	VEC_WRITE(VEC_WSE_RESET, 1);
 	VEC_WRITE(VEC_SOFT_RESET, 1);
@@ -739,6 +731,12 @@ static int vc4_vec_bind(struct device *dev, struct device *master, void *data)
 	if (ret)
 		return ret;
 
+	ret = clk_prepare_enable(vec->clock);
+	if (ret) {
+		DRM_ERROR("Failed to turn on core clock: %d\n", ret);
+		return ret;
+	}
+
 	ret = drmm_encoder_init(drm, &vec->encoder.base,
 				&vc4_vec_encoder_funcs,
 				DRM_MODE_ENCODER_TVDAC,
@@ -757,8 +755,17 @@ static int vc4_vec_bind(struct device *dev, struct device *master, void *data)
 	return 0;
 }
 
+static void vc4_vec_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct vc4_vec *vec = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(vec->clock);
+}
+
 static const struct component_ops vc4_vec_ops = {
 	.bind   = vc4_vec_bind,
+	.unbind = vc4_vec_unbind,
 };
 
 static int vc4_vec_dev_probe(struct platform_device *pdev)
-- 
2.25.1