[PATCH 0/3] Enable DMA on STM32 MCU based on cortex-M7

[PATCH 0/3] Enable DMA on STM32 MCU based on cortex-M7

[Alexandre Torgue]

This series enable DMA on several STM32 MCU based on cortex-M7.
To make it possible, a dedicated dma pool memory area has to be
created. This patchset activate also ARM_MPU flag which will configure 
MPU (Memory Protection Unit) according to devicetree information (mem
and dma-pool). Note that on cortex-M7 DMA has to use a NO cache-able 
memory region.

Regards
Alex


Alexandre Torgue (3):
  ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7
  ARM: configs: stm32: Enable ARM_MPU
  ARM: dts: stm32: enable dma on MCU which embed a cortex-M7

 arch/arm/boot/dts/stm32746g-eval.dts   | 21 +++++++++++++++++++++
 arch/arm/boot/dts/stm32f769-disco.dts  | 21 +++++++++++++++++++++
 arch/arm/boot/dts/stm32h743i-disco.dts | 21 +++++++++++++++++++++
 arch/arm/boot/dts/stm32h743i-eval.dts  | 21 +++++++++++++++++++++
 arch/arm/configs/stm32_defconfig       |  1 +
 5 files changed, 85 insertions(+)

-- 
2.7.4

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[PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

[Alexandre Torgue]

On cortex-M7 MCU, DMA have to use a non cache-able memory area. For this
reason a dedicated memory pool is created for DMA.
This patch creates a DMA memory pool of 1MB of each STM32 MCU which
embeds a cortex-M7 expect stm32f746-disco. Indeed, as stm32f746-disco has
only a 8MB SDRAM and it's tricky to reduce memory used by Kernel.

Signed-off-by: Alexandre Torgue <alexandre.torgue-qxv4g6HH51o@public.gmane.org>

diff --git a/arch/arm/boot/dts/stm32746g-eval.dts b/arch/arm/boot/dts/stm32746g-eval.dts
index 2d4e717..3f52a7b 100644
--- a/arch/arm/boot/dts/stm32746g-eval.dts
+++ b/arch/arm/boot/dts/stm32746g-eval.dts
@@ -57,6 +57,19 @@
 		reg = <0xc0000000 0x2000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		linux,dma {
+			compatible = "shared-dma-pool";
+			linux,dma-default;
+			no-map;
+			reg = <0xc1f00000 0x100000>;
+		};
+	};
+
 	aliases {
 		serial0 = &usart1;
 	};
diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
index 4463ca1..08699a2 100644
--- a/arch/arm/boot/dts/stm32f769-disco.dts
+++ b/arch/arm/boot/dts/stm32f769-disco.dts
@@ -57,6 +57,19 @@
 		reg = <0xC0000000 0x1000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		linux,dma {
+			compatible = "shared-dma-pool";
+			linux,dma-default;
+			no-map;
+			reg = <0xc0f00000 0x100000>;
+		};
+	};
+
 	aliases {
 		serial0 = &usart1;
 	};
diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts b/arch/arm/boot/dts/stm32h743i-disco.dts
index 79e841d..104545a 100644
--- a/arch/arm/boot/dts/stm32h743i-disco.dts
+++ b/arch/arm/boot/dts/stm32h743i-disco.dts
@@ -57,6 +57,19 @@
 		reg = <0xd0000000 0x2000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		linux,dma {
+			compatible = "shared-dma-pool";
+			linux,dma-default;
+			no-map;
+			reg = <0xc1f00000 0x100000>;
+		};
+	};
+
 	aliases {
 		serial0 = &usart2;
 	};
diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts b/arch/arm/boot/dts/stm32h743i-eval.dts
index 9f0e72c..5bd4b16 100644
--- a/arch/arm/boot/dts/stm32h743i-eval.dts
+++ b/arch/arm/boot/dts/stm32h743i-eval.dts
@@ -57,6 +57,19 @@
 		reg = <0xd0000000 0x2000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		linux,dma {
+			compatible = "shared-dma-pool";
+			linux,dma-default;
+			no-map;
+			reg = <0xc1f00000 0x100000>;
+		};
+	};
+
 	aliases {
 		serial0 = &usart1;
 	};
-- 
2.7.4

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[PATCH 2/3] ARM: configs: stm32: Enable ARM_MPU

[Alexandre Torgue]

STM32 MCUs embed a Memory Protection Unit. Enabling this setting will
allow the Kernel to configure the MPU according to devicetree.

Signed-off-by: Alexandre Torgue <alexandre.torgue-qxv4g6HH51o@public.gmane.org>

diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
index bb358ff..e642bdf9 100644
--- a/arch/arm/configs/stm32_defconfig
+++ b/arch/arm/configs/stm32_defconfig
@@ -24,6 +24,7 @@ CONFIG_SET_MEM_PARAM=y
 CONFIG_DRAM_BASE=0x90000000
 CONFIG_FLASH_MEM_BASE=0x08000000
 CONFIG_FLASH_SIZE=0x00200000
+CONFIG_ARM_MPU=y
 CONFIG_PREEMPT=y
 # CONFIG_ATAGS is not set
 CONFIG_ZBOOT_ROM_TEXT=0x0
-- 
2.7.4

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[PATCH 3/3] ARM: dts: stm32: enable dma on MCU which embed a cortex-M7

[Alexandre Torgue]

Enable dma1 and dma2 on:
-stm32746g-eval board
-stm32f769-disco board
-stm32h743i-disco board
-stm32h743i-eval board

Signed-off-by: Alexandre Torgue <alexandre.torgue-qxv4g6HH51o@public.gmane.org>

diff --git a/arch/arm/boot/dts/stm32746g-eval.dts b/arch/arm/boot/dts/stm32746g-eval.dts
index 3f52a7b..2662a27 100644
--- a/arch/arm/boot/dts/stm32746g-eval.dts
+++ b/arch/arm/boot/dts/stm32746g-eval.dts
@@ -113,6 +113,14 @@
 	status = "okay";
 };
 
+&dma1 {
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};
+
 &i2c1 {
 	pinctrl-0 = <&i2c1_pins_b>;
 	pinctrl-names = "default";
diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
index 08699a2..b9b1ffd 100644
--- a/arch/arm/boot/dts/stm32f769-disco.dts
+++ b/arch/arm/boot/dts/stm32f769-disco.dts
@@ -86,6 +86,14 @@
 	clock-frequency = <25000000>;
 };
 
+&dma1 {
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};
+
 &usart1 {
 	pinctrl-0 = <&usart1_pins_a>;
 	pinctrl-names = "default";
diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts b/arch/arm/boot/dts/stm32h743i-disco.dts
index 104545a..2d9e553 100644
--- a/arch/arm/boot/dts/stm32h743i-disco.dts
+++ b/arch/arm/boot/dts/stm32h743i-disco.dts
@@ -79,6 +79,14 @@
 	clock-frequency = <125000000>;
 };
 
+&dma1 {
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};
+
 &usart2 {
 	pinctrl-0 = <&usart2_pins>;
 	pinctrl-names = "default";
diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts b/arch/arm/boot/dts/stm32h743i-eval.dts
index 5bd4b16..3face6a 100644
--- a/arch/arm/boot/dts/stm32h743i-eval.dts
+++ b/arch/arm/boot/dts/stm32h743i-eval.dts
@@ -97,6 +97,14 @@
 	clock-frequency = <25000000>;
 };
 
+&dma1 {
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};
+
 &usart1 {
 	pinctrl-0 = <&usart1_pins>;
 	pinctrl-names = "default";
-- 
2.7.4

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Re: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

[Vladimir Murzin]

On 12/12/17 18:02, Alexandre Torgue wrote:
> On cortex-M7 MCU, DMA have to use a non cache-able memory area. For this
> reason a dedicated memory pool is created for DMA.
> This patch creates a DMA memory pool of 1MB of each STM32 MCU which
> embeds a cortex-M7 expect stm32f746-disco. Indeed, as stm32f746-disco has
                     ^^^^^^
                     except?

> only a 8MB SDRAM and it's tricky to reduce memory used by Kernel.

I guess that 1MB is a kind of "should be enough" estimate, probably something
along with [1] would give you exact numbers...

> 
> Signed-off-by: Alexandre Torgue <alexandre.torgue-qxv4g6HH51o@public.gmane.org>
> 
> diff --git a/arch/arm/boot/dts/stm32746g-eval.dts b/arch/arm/boot/dts/stm32746g-eval.dts
> index 2d4e717..3f52a7b 100644
> --- a/arch/arm/boot/dts/stm32746g-eval.dts
> +++ b/arch/arm/boot/dts/stm32746g-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xc0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
> index 4463ca1..08699a2 100644
> --- a/arch/arm/boot/dts/stm32f769-disco.dts
> +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xC0000000 0x1000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc0f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts b/arch/arm/boot/dts/stm32h743i-disco.dts
> index 79e841d..104545a 100644
> --- a/arch/arm/boot/dts/stm32h743i-disco.dts
> +++ b/arch/arm/boot/dts/stm32h743i-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart2;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts b/arch/arm/boot/dts/stm32h743i-eval.dts
> index 9f0e72c..5bd4b16 100644
> --- a/arch/arm/boot/dts/stm32h743i-eval.dts
> +++ b/arch/arm/boot/dts/stm32h743i-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> 

Usage of dma-default looks correct to me, so FWIW

Reviewed-by: Vladimir Murzin <vladimir.murzin-5wv7dgnIgG8@public.gmane.org>

[1] https://lkml.org/lkml/2017/7/7/296

Vladimir
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Re: [PATCH 2/3] ARM: configs: stm32: Enable ARM_MPU

[Vladimir Murzin]

On 12/12/17 18:02, Alexandre Torgue wrote:
> STM32 MCUs embed a Memory Protection Unit. Enabling this setting will
> allow the Kernel to configure the MPU according to devicetree.

Would it be better to "select ARM_MPU" for machines with Cortex-M7?

Vladimir

> 
> Signed-off-by: Alexandre Torgue <alexandre.torgue-qxv4g6HH51o@public.gmane.org>
> 
> diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
> index bb358ff..e642bdf9 100644
> --- a/arch/arm/configs/stm32_defconfig
> +++ b/arch/arm/configs/stm32_defconfig
> @@ -24,6 +24,7 @@ CONFIG_SET_MEM_PARAM=y
>  CONFIG_DRAM_BASE=0x90000000
>  CONFIG_FLASH_MEM_BASE=0x08000000
>  CONFIG_FLASH_SIZE=0x00200000
> +CONFIG_ARM_MPU=y
>  CONFIG_PREEMPT=y
>  # CONFIG_ATAGS is not set
>  CONFIG_ZBOOT_ROM_TEXT=0x0
> 

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RE: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

[Alexandre TORGUE]

-----Original Message-----
From: Vladimir Murzin [mailto:vladimir.murzin@arm.com] 
Sent: mercredi 13 décembre 2017 11:07
To: Alexandre TORGUE <alexandre.torgue@st.com>; Maxime Coquelin <mcoquelin.stm32@gmail.com>; arnd@arndb.de; robh+dt@kernel.org; mark.rutland@arm.com; linux@armlinux.org.uk; Patrice CHOTARD <patrice.chotard@st.com>; lee.jones@linaro.org
Cc: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

On 12/12/17 18:02, Alexandre Torgue wrote:
> On cortex-M7 MCU, DMA have to use a non cache-able memory area. For 
> this reason a dedicated memory pool is created for DMA.
> This patch creates a DMA memory pool of 1MB of each STM32 MCU which 
> embeds a cortex-M7 expect stm32f746-disco. Indeed, as stm32f746-disco 
> has
                     ^^^^^^
                     except?
Sorry, Is there a typo issue (or just wording issue) ?
 
> only a 8MB SDRAM and it's tricky to reduce memory used by Kernel.

I guess that 1MB is a kind of "should be enough" estimate, probably something along with [1] would give you exact numbers...

Exactly, 1MB is  a kind "should be enough" and code is here to show that we need a dedicated memory area for DMA. But this value has
to be adapt regarding to use case needed by users. Thanks for the lkml link. It will help users to adapt DMA area and thanks for reviewing.

Regards
Alex

> 
> Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
> 
> diff --git a/arch/arm/boot/dts/stm32746g-eval.dts 
> b/arch/arm/boot/dts/stm32746g-eval.dts
> index 2d4e717..3f52a7b 100644
> --- a/arch/arm/boot/dts/stm32746g-eval.dts
> +++ b/arch/arm/boot/dts/stm32746g-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xc0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32f769-disco.dts 
> b/arch/arm/boot/dts/stm32f769-disco.dts
> index 4463ca1..08699a2 100644
> --- a/arch/arm/boot/dts/stm32f769-disco.dts
> +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xC0000000 0x1000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc0f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts 
> b/arch/arm/boot/dts/stm32h743i-disco.dts
> index 79e841d..104545a 100644
> --- a/arch/arm/boot/dts/stm32h743i-disco.dts
> +++ b/arch/arm/boot/dts/stm32h743i-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart2;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts 
> b/arch/arm/boot/dts/stm32h743i-eval.dts
> index 9f0e72c..5bd4b16 100644
> --- a/arch/arm/boot/dts/stm32h743i-eval.dts
> +++ b/arch/arm/boot/dts/stm32h743i-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> 

Usage of dma-default looks correct to me, so FWIW

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

[1] https://lkml.org/lkml/2017/7/7/296

Vladimir

RE: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

[Alexandre TORGUE]

-----Original Message-----
From: Alexandre TORGUE 
Sent: mercredi 13 décembre 2017 11:28
To: 'Vladimir Murzin' <vladimir.murzin@arm.com>; Maxime Coquelin <mcoquelin.stm32@gmail.com>; arnd@arndb.de; robh+dt@kernel.org; mark.rutland@arm.com; linux@armlinux.org.uk; Patrice CHOTARD <patrice.chotard@st.com>; lee.jones@linaro.org
Cc: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org
Subject: RE: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7


-----Original Message-----
From: Vladimir Murzin [mailto:vladimir.murzin@arm.com]
Sent: mercredi 13 décembre 2017 11:07
To: Alexandre TORGUE <alexandre.torgue@st.com>; Maxime Coquelin <mcoquelin.stm32@gmail.com>; arnd@arndb.de; robh+dt@kernel.org; mark.rutland@arm.com; linux@armlinux.org.uk; Patrice CHOTARD <patrice.chotard@st.com>; lee.jones@linaro.org
Cc: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] ARM: dts: stm32: add DMA memory pool on MCU which embed a cortex-M7

On 12/12/17 18:02, Alexandre Torgue wrote:
> On cortex-M7 MCU, DMA have to use a non cache-able memory area. For 
> this reason a dedicated memory pool is created for DMA.
> This patch creates a DMA memory pool of 1MB of each STM32 MCU which 
> embeds a cortex-M7 expect stm32f746-disco. Indeed, as stm32f746-disco 
> has
                     ^^^^^^
                     except?
Sorry, Is there a typo issue (or just wording issue) ?

Sorry I was not awake this morning. If no v2 I will fix this typo when I will apply patch on my tree.

 
> only a 8MB SDRAM and it's tricky to reduce memory used by Kernel.

I guess that 1MB is a kind of "should be enough" estimate, probably something along with [1] would give you exact numbers...

Exactly, 1MB is  a kind "should be enough" and code is here to show that we need a dedicated memory area for DMA. But this value has to be adapt regarding to use case needed by users. Thanks for the lkml link. It will help users to adapt DMA area and thanks for reviewing.

Regards
Alex

> 
> Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
> 
> diff --git a/arch/arm/boot/dts/stm32746g-eval.dts
> b/arch/arm/boot/dts/stm32746g-eval.dts
> index 2d4e717..3f52a7b 100644
> --- a/arch/arm/boot/dts/stm32746g-eval.dts
> +++ b/arch/arm/boot/dts/stm32746g-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xc0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32f769-disco.dts
> b/arch/arm/boot/dts/stm32f769-disco.dts
> index 4463ca1..08699a2 100644
> --- a/arch/arm/boot/dts/stm32f769-disco.dts
> +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xC0000000 0x1000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc0f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts
> b/arch/arm/boot/dts/stm32h743i-disco.dts
> index 79e841d..104545a 100644
> --- a/arch/arm/boot/dts/stm32h743i-disco.dts
> +++ b/arch/arm/boot/dts/stm32h743i-disco.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart2;
>  	};
> diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts
> b/arch/arm/boot/dts/stm32h743i-eval.dts
> index 9f0e72c..5bd4b16 100644
> --- a/arch/arm/boot/dts/stm32h743i-eval.dts
> +++ b/arch/arm/boot/dts/stm32h743i-eval.dts
> @@ -57,6 +57,19 @@
>  		reg = <0xd0000000 0x2000000>;
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc1f00000 0x100000>;
> +		};
> +	};
> +
>  	aliases {
>  		serial0 = &usart1;
>  	};
> 

Usage of dma-default looks correct to me, so FWIW

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

[1] https://lkml.org/lkml/2017/7/7/296

Vladimir
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Re: [PATCH 2/3] ARM: configs: stm32: Enable ARM_MPU

[Alexandre Torgue]

Hi Vlad

On 12/13/2017 11:11 AM, Vladimir Murzin wrote:
> On 12/12/17 18:02, Alexandre Torgue wrote:
>> STM32 MCUs embed a Memory Protection Unit. Enabling this setting will
>> allow the Kernel to configure the MPU according to devicetree.
> 
> Would it be better to "select ARM_MPU" for machines with Cortex-M7?

Sorry for this late answer. You are right I will use a "select" only for 
stm32f7 and stm32h7 machines in mach-stm32/Kconfig.

Regards
Alex

> 
> Vladimir
> 
>>
>> Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
>>
>> diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
>> index bb358ff..e642bdf9 100644
>> --- a/arch/arm/configs/stm32_defconfig
>> +++ b/arch/arm/configs/stm32_defconfig
>> @@ -24,6 +24,7 @@ CONFIG_SET_MEM_PARAM=y
>>   CONFIG_DRAM_BASE=0x90000000
>>   CONFIG_FLASH_MEM_BASE=0x08000000
>>   CONFIG_FLASH_SIZE=0x00200000
>> +CONFIG_ARM_MPU=y
>>   CONFIG_PREEMPT=y
>>   # CONFIG_ATAGS is not set
>>   CONFIG_ZBOOT_ROM_TEXT=0x0
>>
>