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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Joerg Albert <joerg.albert@iav.de>,
        Lucas Stach <l.stach@pengutronix.de>,
        Christian Gmeiner <christian.gmeiner@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0694/1039] drm/etnaviv: consider completed fence seqno in hang check
Date:   Mon, 24 Jan 2022 19:41:23 +0100
Message-Id: <20220124184148.671759759@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
References: <20220124184125.121143506@linuxfoundation.org>
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From: Lucas Stach <l.stach@pengutronix.de>

[ Upstream commit cdd156955f946beaa5f3a00d8ccf90e5a197becc ]

Some GPU heavy test programs manage to trigger the hangcheck quite often.
If there are no other GPU users in the system and the test program
exhibits a very regular structure in the commandstreams that are being
submitted, we can end up with two distinct submits managing to trigger
the hangcheck with the FE in a very similar address range. This leads
the hangcheck to believe that the GPU is stuck, while in reality the GPU
is already busy working on a different job. To avoid those spurious
GPU resets, also remember and consider the last completed fence seqno
in the hang check.

Reported-by: Joerg Albert <joerg.albert@iav.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/etnaviv/etnaviv_gpu.h   | 1 +
 drivers/gpu/drm/etnaviv/etnaviv_sched.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
index 1c75c8ed5bcea..85eddd492774d 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
@@ -130,6 +130,7 @@ struct etnaviv_gpu {
 
 	/* hang detection */
 	u32 hangcheck_dma_addr;
+	u32 hangcheck_fence;
 
 	void __iomem *mmio;
 	int irq;
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sched.c b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
index 180bb633d5c53..58f593b278c15 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
@@ -107,8 +107,10 @@ static enum drm_gpu_sched_stat etnaviv_sched_timedout_job(struct drm_sched_job
 	 */
 	dma_addr = gpu_read(gpu, VIVS_FE_DMA_ADDRESS);
 	change = dma_addr - gpu->hangcheck_dma_addr;
-	if (change < 0 || change > 16) {
+	if (gpu->completed_fence != gpu->hangcheck_fence ||
+	    change < 0 || change > 16) {
 		gpu->hangcheck_dma_addr = dma_addr;
+		gpu->hangcheck_fence = gpu->completed_fence;
 		goto out_no_timeout;
 	}
 
-- 
2.34.1