drm/etnaviv: set up initial PULSE_EATER register

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.
Signed-off-by: Wladimir J. van der Laan <laanwj@gmail.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -546,6 +546,37 @@ void etnaviv_gpu_start_fe(struct etnaviv_gpu *gpu, u32 address, u16 prefetch)
 		  VIVS_FE_COMMAND_CONTROL_PREFETCH(prefetch));
 }
 
+static void etnaviv_gpu_setup_pulse_eater(struct etnaviv_gpu *gpu)
+{
+	/*
+	 * Base value for VIVS_PM_PULSE_EATER register on models where it
+	 * cannot be read, extracted from vivante kernel driver.
+	 */
+	u32 pulse_eater = 0x01590880;
+
+	if (etnaviv_is_model_rev(gpu, GC4000, 0x5208) ||
+	    etnaviv_is_model_rev(gpu, GC4000, 0x5222)) {
+		pulse_eater |= BIT(23);
+
+	}
+
+	if (etnaviv_is_model_rev(gpu, GC1000, 0x5039) ||
+	    etnaviv_is_model_rev(gpu, GC1000, 0x5040)) {
+		pulse_eater &= ~BIT(16);
+		pulse_eater |= BIT(17);
+	}
+
+	if ((gpu->identity.revision > 0x5420) &&
+	    (gpu->identity.features & chipFeatures_PIPE_3D))
+	{
+		/* Performance fix: disable internal DFS */
+		pulse_eater = gpu_read(gpu, VIVS_PM_PULSE_EATER);
+		pulse_eater |= BIT(18);
+	}
+
+	gpu_write(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
+}
+
 static void etnaviv_gpu_hw_init(struct etnaviv_gpu *gpu)
 {
 	u16 prefetch;
@@ -586,6 +617,9 @@ static void etnaviv_gpu_hw_init(struct etnaviv_gpu *gpu)
 		gpu_write(gpu, VIVS_MC_BUS_CONFIG, bus_config);
 	}
 
+	/* setup the pulse eater */
+	etnaviv_gpu_setup_pulse_eater(gpu);
+
 	/* setup the MMU */
 	etnaviv_iommu_restore(gpu);