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.

Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220525145754.25866-5-alyssa.rosenzweig@collabora.com

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
+	/* If an occlusion query write causes a bus fault on affected GPUs,
-	 * might change.
+	 * 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;
 }
 

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
 };