linux-kernel - [PATCH v2 4/9] drm/panfrost: Handle HW_ISSUE_TTRX

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Date:   Wed, 25 May 2022 10:57:49 -0400
From:   Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Rob Herring <robh@...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>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/9] drm/panfrost: Handle HW_ISSUE_TTRX_3076

Some Valhall GPUs require resets when encountering bus faults due to
occlusion query writes. Add the issue bit for this and handle it.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
Reviewed-by: Steven Price <steven.price@....com>
---
 drivers/gpu/drm/panfrost/panfrost_device.c | 9 +++++++--
 drivers/gpu/drm/panfrost/panfrost_issues.h | 4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index 7f51a4682ccb..ee612303f076 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -11,6 +11,7 @@
 #include "panfrost_device.h"
 #include "panfrost_devfreq.h"
 #include "panfrost_features.h"
+#include "panfrost_issues.h"
 #include "panfrost_gpu.h"
 #include "panfrost_job.h"
 #include "panfrost_mmu.h"
@@ -380,9 +381,13 @@ const char *panfrost_exception_name(u32 exception_code)
 bool panfrost_exception_needs_reset(const struct panfrost_device *pfdev,
 				    u32 exception_code)
 {
-	/* Right now, none of the GPU we support need a reset, but this
-	 * might change.
+	/* If an occlusion query write causes a bus fault on affected GPUs,
+	 * future fragment jobs may hang. Reset to workaround.
 	 */
+	if (exception_code == DRM_PANFROST_EXCEPTION_JOB_BUS_FAULT)
+		return panfrost_has_hw_issue(pfdev, HW_ISSUE_TTRX_3076);
+
+	/* No other GPUs we support need a reset */
 	return false;
 }
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_issues.h b/drivers/gpu/drm/panfrost/panfrost_issues.h
index 14670ee58ace..e35807e4b743 100644
--- a/drivers/gpu/drm/panfrost/panfrost_issues.h
+++ b/drivers/gpu/drm/panfrost/panfrost_issues.h
@@ -128,6 +128,10 @@ enum panfrost_hw_issue {
 	/* Must set SC_VAR_ALGORITHM */
 	HW_ISSUE_TTRX_2968_TTRX_3162,
 
+	/* Bus fault from occlusion query write may cause future fragment jobs
+	 * to hang */
+	HW_ISSUE_TTRX_3076,
+
 	HW_ISSUE_END
 };
 
-- 
2.35.1