[PATCH 0/2 v2] drm/arcpgu: Get use of dedicated memory area for frame buffer

[PATCH 0/2 v2] drm/arcpgu: Get use of dedicated memory area for frame buffer

[Alexey Brodkin]

This mini-series allows to allocate frame buffer memory in desired
location. 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.

Cc: Dave Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: devicetree@vger.kernel.org

Changes v1 -> v2:
 * Reserved memory size bumped from 16Mb to 32Mb.

 * Reserved area in AXS103 boards moved to the very end of available DDR.

Alexey Brodkin (2):
  drm/arcpgu: use dedicated memory area for frame buffer
  ARC: [axs10x] Specify reserved memory for frame buffer

 arch/arc/boot/dts/axc001.dtsi     | 22 ++++++++++++++++++++--
 arch/arc/boot/dts/axc003.dtsi     | 14 ++++++++++++++
 arch/arc/boot/dts/axc003_idu.dtsi | 14 ++++++++++++++
 arch/arc/boot/dts/axs10x_mb.dtsi  |  2 +-
 drivers/gpu/drm/arc/arcpgu_drv.c  |  6 ++++++
 5 files changed, 55 insertions(+), 3 deletions(-)

-- 
2.5.5

[PATCH 1/2 v2] drm/arcpgu: use dedicated memory area for frame buffer

[Alexey Brodkin]

Now when ARC supports reserved memory areas and
per-device coherent DMA allocations we may switch ARC PGU
to use of those dedicated areas.

One of the benefits we may move frame-buffer area out
from IO Coherency aperture and so significantly
reduce IOC utilization allowing less demanding
peripherals to use all perks of IOC.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
---

No changes v1 -> v2.

 drivers/gpu/drm/arc/arcpgu_drv.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/arc/arcpgu_drv.c b/drivers/gpu/drm/arc/arcpgu_drv.c
index 5b35e5db..76e187a 100644
--- a/drivers/gpu/drm/arc/arcpgu_drv.c
+++ b/drivers/gpu/drm/arc/arcpgu_drv.c
@@ -19,6 +19,7 @@
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_atomic_helper.h>
+#include <linux/of_reserved_mem.h>
 
 #include "arcpgu.h"
 #include "arcpgu_regs.h"
@@ -135,6 +136,11 @@ static int arcpgu_load(struct drm_device *drm)
 	dev_info(drm->dev, "arc_pgu ID: 0x%x\n",
 		 arc_pgu_read(arcpgu, ARCPGU_REG_ID));
 
+	/* Get the optional framebuffer memory resource */
+	ret = of_reserved_mem_device_init(drm->dev);
+	if (ret && ret != -ENODEV)
+		return ret;
+
 	if (dma_set_mask_and_coherent(drm->dev, DMA_BIT_MASK(32)))
 		return -ENODEV;
 
-- 
2.5.5

[PATCH 2/2 v2] ARC: [axs10x] Specify reserved memory for frame buffer

[Alexey Brodkin]

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>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: devicetree@vger.kernel.org
---

Changes v1 -> v2:
 * Reserved memory size bumped from 16Mb to 32Mb.
   Given the corner case 1920x1080x24bpp and tripl-buffering
   we'll need ~18Mb in the future so let's reserve 32Mb today
   and don't think about that any more.

 * Reserved area in AXS103 boards moved to the very end of the first Gb.
   Even though we use only 512Mb for kernel on AXS103 board
   we have 1Gb of DDR really. So let's move reserved area in the very
   end of available mamory. This way we'll be able to keep this mapping
   when we'll want to use > 512Mb in the kernel.

 * And while at it correct "ranges" value for AXS101 board: we do have
   only 512 Mb of DDR on the board so let's not temp users to try to use more.

 arch/arc/boot/dts/axc001.dtsi     | 22 ++++++++++++++++++++--
 arch/arc/boot/dts/axc003.dtsi     | 14 ++++++++++++++
 arch/arc/boot/dts/axc003_idu.dtsi | 14 ++++++++++++++
 arch/arc/boot/dts/axs10x_mb.dtsi  |  2 +-
 4 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/arch/arc/boot/dts/axc001.dtsi b/arch/arc/boot/dts/axc001.dtsi
index 420dcfd..262496a 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 f90fadf..35ece04 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 06a9f29..df9ddb6 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 823f15c..64b063d 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>;
-- 
2.5.5

Re: [PATCH 2/2 v2] ARC: [axs10x] Specify reserved memory for frame buffer

[Vineet Gupta]

On Thursday 28 April 2016 07:49 PM, Alexey Brodkin wrote:
> 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>