drm/panfrost: Handle IDVS_GROUP_SIZE feature

The IDVS group size feature was missing. It is used on some Bifrost and
Valhall GPUs, and is the last kernel-relevant Bifrost feature we're
missing.

This feature adds an extra IDVS group size field to the JM_CONFIG
register. In kbase, the value is configurable via the device tree; kbase
uses 0xF as a default if no value is specified. Until we find a device
demanding otherwise, let's always set the 0xF default on devices which
support this feature mimicking kbase's behaviour.

Tuning this register slightly improves performance of index-driven
vertex shading. On Mali-G52 (with Mesa), overall glmark2 score is
improved from 1026 to 1037. Geometry-heavy scenes like -bshading are
improved from 1068 to 1098.
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220211145849.3148-1-alyssa.rosenzweig@collabora.com

drivers/gpu/drm/panfrost/panfrost_features.h

@@ -20,6 +20,7 @@ enum panfrost_hw_feature {
 	HW_FEATURE_AARCH64_MMU,
 	HW_FEATURE_TLS_HASHING,
 	HW_FEATURE_THREAD_GROUP_SPLIT,
+	HW_FEATURE_IDVS_GROUP_SIZE,
 	HW_FEATURE_3BIT_EXT_RW_L2_MMU_CONFIG,
 };
 
@@ -74,6 +75,7 @@ enum panfrost_hw_feature {
 	BIT_ULL(HW_FEATURE_FLUSH_REDUCTION) | \
 	BIT_ULL(HW_FEATURE_PROTECTED_MODE) | \
 	BIT_ULL(HW_FEATURE_PROTECTED_DEBUG_MODE) | \
+	BIT_ULL(HW_FEATURE_IDVS_GROUP_SIZE) | \
 	BIT_ULL(HW_FEATURE_COHERENCY_REG))
 
 #define hw_features_g76 (\
@@ -87,6 +89,7 @@ enum panfrost_hw_feature {
 	BIT_ULL(HW_FEATURE_COHERENCY_REG) | \
 	BIT_ULL(HW_FEATURE_AARCH64_MMU) | \
 	BIT_ULL(HW_FEATURE_TLS_HASHING) | \
+	BIT_ULL(HW_FEATURE_IDVS_GROUP_SIZE) | \
 	BIT_ULL(HW_FEATURE_3BIT_EXT_RW_L2_MMU_CONFIG))
 
 #define hw_features_g31 (\

drivers/gpu/drm/panfrost/panfrost_gpu.c

@@ -145,6 +145,9 @@ static void panfrost_gpu_init_quirks(struct panfrost_device *pfdev)
 		quirks |= (COHERENCY_ACE_LITE | COHERENCY_ACE) <<
 			   JM_FORCE_COHERENCY_FEATURES_SHIFT;
 
+	if (panfrost_has_hw_feature(pfdev, HW_FEATURE_IDVS_GROUP_SIZE))
+		quirks |= JM_DEFAULT_IDVS_GROUP_SIZE << JM_IDVS_GROUP_SIZE_SHIFT;
+
 	if (quirks)
 		gpu_write(pfdev, GPU_JM_CONFIG, quirks);
 

drivers/gpu/drm/panfrost/panfrost_regs.h

@@ -208,6 +208,7 @@
 #define JM_MAX_JOB_THROTTLE_LIMIT	0x3F
 #define JM_FORCE_COHERENCY_FEATURES_SHIFT 2
 #define JM_IDVS_GROUP_SIZE_SHIFT	16
+#define JM_DEFAULT_IDVS_GROUP_SIZE	0xF
 #define JM_MAX_IDVS_GROUP_SIZE		0x3F