ARC: [axs10x] Specify reserved memory for frame buffer

Allocation of a frame buffer memory in a special memory region
allows bypassing of so-called IO Coherency aperture
which is typically set as a range 0x8z-0xAz.

I.e. all data traffic to PGU bypasses IO Coherency block
and saves its bandwidth for other peripherals.

Even though for AXS101 (which sorts ARC770 CPU) IOC is not
an option for a sake of keeping one DT description for the
base-board (axs10x_mb.dtsi) we're still defining reserved
memory location in the very end of DDR.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Cc: devicetree@vger.kernel.org

4 files changed, 49 insertions, 3 deletions

diff --git a/arch/arc/boot/dts/axc001.dtsi b/arch/arc/boot/dts/axc001.dtsi
index 420dcfde289f..262496ac2628 100644
--- a/arch/arc/boot/dts/axc001.dtsi
+++ b/arch/arc/boot/dts/axc001.dtsi
@@ -93,8 +93,26 @@
         memory {
                 #address-cells = <1>;
                 #size-cells = <1>;
-                ranges = <0x00000000 0x80000000 0x40000000>;
+                ranges = <0x00000000 0x80000000 0x20000000>;
                 device_type = "memory";
-                reg = <0x80000000 0x20000000>;  /* 512MiB */
+                reg = <0x80000000 0x1b000000>;  /* (512 - 32) MiB */
+        };
+
+        reserved-memory {
+                #address-cells = <1>;
+                #size-cells = <1>;
+                ranges;
+                /*
+                 * We just move frame buffer area to the very end of
+                 * available DDR. And even though in case of ARC770 there's
+                 * no strict requirement for a frame-buffer to be in any
+                 * particular location it allows us to use the same
+                 * base board's DT node for ARC PGU as for ARc HS38.
+                 */
+                frame_buffer: frame_buffer@9e000000 {
+                        compatible = "shared-dma-pool";
+                        reg = <0x9e000000 0x2000000>;
+                        no-map;
+                };
         };
 };
diff --git a/arch/arc/boot/dts/axc003.dtsi b/arch/arc/boot/dts/axc003.dtsi
index f90fadf7f94e..35ece04d8353 100644
--- a/arch/arc/boot/dts/axc003.dtsi
+++ b/arch/arc/boot/dts/axc003.dtsi
@@ -100,4 +100,18 @@
                 device_type = "memory";
                 reg = <0x80000000 0x20000000>;  /* 512MiB */
         };
+
+        reserved-memory {
+                #address-cells = <1>;
+                #size-cells = <1>;
+                ranges;
+                /*
+                 * Move frame buffer out of IOC aperture (0x8z-0xAz).
+                 */
+                frame_buffer: frame_buffer@be000000 {
+                        compatible = "shared-dma-pool";
+                        reg = <0xbe000000 0x2000000>;
+                        no-map;
+                };
+        };
 };
diff --git a/arch/arc/boot/dts/axc003_idu.dtsi b/arch/arc/boot/dts/axc003_idu.dtsi
index 06a9f294a2e6..df9ddb623bfe 100644
--- a/arch/arc/boot/dts/axc003_idu.dtsi
+++ b/arch/arc/boot/dts/axc003_idu.dtsi
@@ -123,4 +123,18 @@
                 device_type = "memory";
                 reg = <0x80000000 0x20000000>;  /* 512MiB */
         };
+
+        reserved-memory {
+                #address-cells = <1>;
+                #size-cells = <1>;
+                ranges;
+                /*
+                 * Move frame buffer out of IOC aperture (0x8z-0xAz).
+                 */
+                frame_buffer: frame_buffer@be000000 {
+                        compatible = "shared-dma-pool";
+                        reg = <0xbe000000 0x2000000>;
+                        no-map;
+                };
+        };
 };
diff --git a/arch/arc/boot/dts/axs10x_mb.dtsi b/arch/arc/boot/dts/axs10x_mb.dtsi
index 823f15ca68df..64b063d4e996 100644
--- a/arch/arc/boot/dts/axs10x_mb.dtsi
+++ b/arch/arc/boot/dts/axs10x_mb.dtsi
@@ -283,7 +283,7 @@
                         encoder-slave = <&adv7511>;
                         clocks = <&pguclk>;
                         clock-names = "pxlclk";
-
+                        memory-region = <&frame_buffer>;
                         port {
                                 pgu_output: endpoint {
                                         remote-endpoint = <&adv7511_input>;