[PATCH] drm/etnaviv: Set up initial PULSE_EATER register

["Wladimir J. van der Laan" <laanwj@gmail.com>]

Set up the PULSE_EATER register (0x0010C) in etnaviv_gpu_hw_init. This
ports three mostly undocumented model/revision-specific register
overrides from the Vivante kernel driver.

This is relevant as at least the "disable internal DFS" for revisions >
0x5420 has shown to have a huge impact on shader performance (sped up
memory read performance by 7.5x and write performance by 1.5x) on an
affected GPU.
---
 drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index 1e0ec81..e1a9d64 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -548,6 +548,9 @@ void etnaviv_gpu_start_fe(struct etnaviv_gpu *gpu, u32 address, u16 prefetch)
 		  VIVS_FE_COMMAND_CONTROL_PREFETCH(prefetch));
 }
 
+/* base value for VIVS_PM_PULSE_EATER register on models where it cannot be read */
+#define PULSE_EATER_BASE_VALUE (0x01590880)
+
 static void etnaviv_gpu_hw_init(struct etnaviv_gpu *gpu)
 {
 	u16 prefetch;
@@ -588,6 +591,33 @@ static void etnaviv_gpu_hw_init(struct etnaviv_gpu *gpu)
 		gpu_write(gpu, VIVS_MC_BUS_CONFIG, bus_config);
 	}
 
+	/* set up the pulse eater */
+	if (etnaviv_is_model_rev(gpu, GC4000, 0x5208) ||
+	    etnaviv_is_model_rev(gpu, GC4000, 0x5222)) {
+		/* undocumented workaround from vivante kernel driver */
+		u32 pulse_eater = PULSE_EATER_BASE_VALUE;
+		pulse_eater |= BIT(23);
+		gpu_write(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
+	}
+
+	if (etnaviv_is_model_rev(gpu, GC1000, 0x5039) ||
+	    etnaviv_is_model_rev(gpu, GC1000, 0x5040)) {
+		/* undocumented workaround from vivante kernel driver */
+		u32 pulse_eater = PULSE_EATER_BASE_VALUE;
+		pulse_eater &= ~BIT(16);
+		pulse_eater |= BIT(17);
+		gpu_write(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
+	}
+
+	if ((gpu->identity.revision > 0x5420) &&
+            (gpu->identity.features & chipFeatures_PIPE_3D))
+	{
+		/* disable internal DFS: this is extremely important to performance */
+		u32 pulse_eater = gpu_read(gpu, VIVS_PM_PULSE_EATER);
+		pulse_eater |= BIT(18);
+		gpu_write(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
+	}
+
 	/* setup the MMU */
 	etnaviv_iommu_restore(gpu);
 
-- 
2.7.4

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