drm/arm/mali-dp: Add display QoS interface configuration for Mali DP500

Configure the display Quality of service (QoS) levels priority if the
optional property node "arm,malidp-aqros-value" is defined in DTS file.

QoS signaling using AQROS and AWQOS AXI interface signals, the AQROS is
driven from the "RQOS" register, so needed to program the RQOS register
to avoid the high resolutions flicker issue on the LS1028A platform.
Signed-off-by: Wen He <wen.he_1@nxp.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190910075913.17650-2-wen.he_1@nxp.com

drivers/gpu/drm/arm/malidp_drv.c

@@ -817,6 +817,12 @@ static int malidp_bind(struct device *dev)
 
 	malidp->core_id = version;
 
+	ret = of_property_read_u32(dev->of_node,
+					"arm,malidp-arqos-value",
+					&hwdev->arqos_value);
+	if (ret)
+		hwdev->arqos_value = 0x0;
+
 	/* set the number of lines used for output of RGB data */
 	ret = of_property_read_u8_array(dev->of_node,
 					"arm,malidp-output-port-lines",

drivers/gpu/drm/arm/malidp_hw.c

@@ -379,6 +379,15 @@ static void malidp500_modeset(struct malidp_hw_device *hwdev, struct videomode *
 		malidp_hw_setbits(hwdev, MALIDP_DISP_FUNC_ILACED, MALIDP_DE_DISPLAY_FUNC);
 	else
 		malidp_hw_clearbits(hwdev, MALIDP_DISP_FUNC_ILACED, MALIDP_DE_DISPLAY_FUNC);
+
+	/*
+	 * Program the RQoS register to avoid high resolutions flicker
+	 * issue on the LS1028A.
+	 */
+	if (hwdev->arqos_value) {
+		val = hwdev->arqos_value;
+		malidp_hw_setbits(hwdev, val, MALIDP500_RQOS_QUALITY);
+	}
 }
 
 int malidp_format_get_bpp(u32 fmt)

drivers/gpu/drm/arm/malidp_hw.h

@@ -251,6 +251,9 @@ struct malidp_hw_device {
 
 	/* size of memory used for rotating layers, up to two banks available */
 	u32 rotation_memory[2];
+
+	/* priority level of RQOS register used for driven the ARQOS signal */
+	u32 arqos_value;
 };
 
 static inline u32 malidp_hw_read(struct malidp_hw_device *hwdev, u32 reg)

drivers/gpu/drm/arm/malidp_regs.h

@@ -210,6 +210,16 @@
 #define MALIDP500_CONFIG_VALID		0x00f00
 #define MALIDP500_CONFIG_ID		0x00fd4
 
+/*
+ * The quality of service (QoS) register on the DP500. RQOS register values
+ * are driven by the ARQOS signal, using AXI transacations, dependent on the
+ * FIFO input level.
+ * The RQOS register can also set QoS levels for:
+ *    - RED_ARQOS   @ A 4-bit signal value for close to underflow conditions
+ *    - GREEN_ARQOS @ A 4-bit signal value for normal conditions
+ */
+#define MALIDP500_RQOS_QUALITY          0x00500
+
 /* register offsets and bits specific to DP550/DP650 */
 #define MALIDP550_ADDR_SPACE_SIZE	0x10000
 #define MALIDP550_DE_CONTROL		0x00010