[PATCH v3 3/3] media: verisilicon: Avoid G2 bus error while decoding H.264 and HEVC

[ming.qian@oss.nxp.com]

From: Ming Qian <ming.qian@oss.nxp.com>

For the i.MX8MQ platform, there is a hardware limitation: the g1 VPU and
g2 VPU cannot decode simultaneously; otherwise, it will cause below bus
error and produce corrupted pictures, even potentially lead to system hang.

[  110.527986] hantro-vpu 38310000.video-codec: frame decode timed out.
[  110.583517] hantro-vpu 38310000.video-codec: bus error detected.

Therefore, it is necessary to ensure that g1 and g2 operate alternately.
This allows for successful multi-instance decoding of H.264 and HEVC.

To achieve this, we can have g1 and g2 share the same v4l2_m2m_dev, and
then the v4l2_m2m_dev can handle the scheduling.

Fixes: cb5dd5a0fa518 ("media: hantro: Introduce G2/HEVC decoder")
Co-developed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Ming Qian <ming.qian@oss.nxp.com>
---
v3
- Apply Nicolas's approach that use an array list to define the shared
  devices

v2
- Abandon the waiting approach.
- Switch to a shared v4l2_m2m_dev solution.

 drivers/media/platform/verisilicon/hantro.h   |  2 +
 .../media/platform/verisilicon/hantro_drv.c   | 42 +++++++++++++++++--
 .../media/platform/verisilicon/imx8m_vpu_hw.c |  8 ++++
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/verisilicon/hantro.h b/drivers/media/platform/verisilicon/hantro.h
index e0fdc4535b2d..0353de154a1e 100644
--- a/drivers/media/platform/verisilicon/hantro.h
+++ b/drivers/media/platform/verisilicon/hantro.h
@@ -77,6 +77,7 @@ struct hantro_irq {
  * @double_buffer:		core needs double buffering
  * @legacy_regs:		core uses legacy register set
  * @late_postproc:		postproc must be set up at the end of the job
+ * @shared_devices:		an array of device ids that cannot run concurrently
  */
 struct hantro_variant {
 	unsigned int enc_offset;
@@ -101,6 +102,7 @@ struct hantro_variant {
 	unsigned int double_buffer : 1;
 	unsigned int legacy_regs : 1;
 	unsigned int late_postproc : 1;
+	const struct of_device_id *shared_devices;
 };
 
 /**
diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
index 60b95b5d8565..70160eaf3d15 100644
--- a/drivers/media/platform/verisilicon/hantro_drv.c
+++ b/drivers/media/platform/verisilicon/hantro_drv.c
@@ -13,6 +13,7 @@
 #include <linux/clk.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
@@ -1035,6 +1036,41 @@ static int hantro_disable_multicore(struct hantro_dev *vpu)
 	return 0;
 }
 
+static struct v4l2_m2m_dev *hantro_get_v4l2_m2m_dev(struct hantro_dev *vpu)
+{
+	struct device_node *node;
+	struct hantro_dev *shared_vpu;
+
+	if (!vpu->variant || !vpu->variant->shared_devices)
+		goto init_new_m2m_dev;
+
+	for_each_matching_node(node, vpu->variant->shared_devices) {
+		struct platform_device *pdev;
+		struct v4l2_m2m_dev *m2m_dev;
+
+		pdev = of_find_device_by_node(node);
+		of_node_put(node);
+
+		if (!pdev)
+			continue;
+
+		shared_vpu = platform_get_drvdata(pdev);
+		if (IS_ERR_OR_NULL(shared_vpu) || shared_vpu == vpu) {
+			platform_device_put(pdev);
+			continue;
+		}
+
+		v4l2_m2m_get(shared_vpu->m2m_dev);
+		m2m_dev = shared_vpu->m2m_dev;
+		platform_device_put(pdev);
+
+		return m2m_dev;
+	}
+
+init_new_m2m_dev:
+	return v4l2_m2m_init(&vpu_m2m_ops);
+}
+
 static int hantro_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
@@ -1186,7 +1222,7 @@ static int hantro_probe(struct platform_device *pdev)
 	}
 	platform_set_drvdata(pdev, vpu);
 
-	vpu->m2m_dev = v4l2_m2m_init(&vpu_m2m_ops);
+	vpu->m2m_dev = hantro_get_v4l2_m2m_dev(vpu);
 	if (IS_ERR(vpu->m2m_dev)) {
 		v4l2_err(&vpu->v4l2_dev, "Failed to init mem2mem device\n");
 		ret = PTR_ERR(vpu->m2m_dev);
@@ -1225,7 +1261,7 @@ static int hantro_probe(struct platform_device *pdev)
 	hantro_remove_enc_func(vpu);
 err_m2m_rel:
 	media_device_cleanup(&vpu->mdev);
-	v4l2_m2m_release(vpu->m2m_dev);
+	v4l2_m2m_put(vpu->m2m_dev);
 err_v4l2_unreg:
 	v4l2_device_unregister(&vpu->v4l2_dev);
 err_clk_unprepare:
@@ -1248,7 +1284,7 @@ static void hantro_remove(struct platform_device *pdev)
 	hantro_remove_dec_func(vpu);
 	hantro_remove_enc_func(vpu);
 	media_device_cleanup(&vpu->mdev);
-	v4l2_m2m_release(vpu->m2m_dev);
+	v4l2_m2m_put(vpu->m2m_dev);
 	v4l2_device_unregister(&vpu->v4l2_dev);
 	clk_bulk_unprepare(vpu->variant->num_clocks, vpu->clocks);
 	reset_control_assert(vpu->resets);
diff --git a/drivers/media/platform/verisilicon/imx8m_vpu_hw.c b/drivers/media/platform/verisilicon/imx8m_vpu_hw.c
index 5be0e2e76882..6f8e43b7f157 100644
--- a/drivers/media/platform/verisilicon/imx8m_vpu_hw.c
+++ b/drivers/media/platform/verisilicon/imx8m_vpu_hw.c
@@ -343,6 +343,12 @@ const struct hantro_variant imx8mq_vpu_variant = {
 	.num_regs = ARRAY_SIZE(imx8mq_reg_names)
 };
 
+static const struct of_device_id imx8mq_vpu_shared_resources[] __initconst = {
+	{ .compatible = "nxp,imx8mq-vpu-g1", },
+	{ .compatible = "nxp,imx8mq-vpu-g2", },
+	{ /* sentinel */ }
+};
+
 const struct hantro_variant imx8mq_vpu_g1_variant = {
 	.dec_fmts = imx8m_vpu_dec_fmts,
 	.num_dec_fmts = ARRAY_SIZE(imx8m_vpu_dec_fmts),
@@ -356,6 +362,7 @@ const struct hantro_variant imx8mq_vpu_g1_variant = {
 	.num_irqs = ARRAY_SIZE(imx8mq_irqs),
 	.clk_names = imx8mq_g1_clk_names,
 	.num_clocks = ARRAY_SIZE(imx8mq_g1_clk_names),
+	.shared_devices = imx8mq_vpu_shared_resources,
 };
 
 const struct hantro_variant imx8mq_vpu_g2_variant = {
@@ -371,6 +378,7 @@ const struct hantro_variant imx8mq_vpu_g2_variant = {
 	.num_irqs = ARRAY_SIZE(imx8mq_g2_irqs),
 	.clk_names = imx8mq_g2_clk_names,
 	.num_clocks = ARRAY_SIZE(imx8mq_g2_clk_names),
+	.shared_devices = imx8mq_vpu_shared_resources,
 };
 
 const struct hantro_variant imx8mm_vpu_g1_variant = {
-- 
2.52.0