linux-kernel - Re: [PATCH v3 05/12] dt-bindings: soc: Add Aspeed XDMA Engine

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Message-ID: <45cabf88-063d-aea1-6c2b-fa8cc0d8cbd3@linux.ibm.com>
Date:   Thu, 19 Dec 2019 09:48:43 -0600
From:   Eddie James <eajames@...ux.ibm.com>
To:     Andrew Jeffery <andrew@...id.au>, linux-aspeed@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        mark.rutland@....com, Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, tglx@...utronix.de,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH v3 05/12] dt-bindings: soc: Add Aspeed XDMA Engine


On 12/18/19 5:12 PM, Andrew Jeffery wrote:
>
> On Thu, 19 Dec 2019, at 01:39, Eddie James wrote:
>> Document the bindings for the Aspeed AST25XX and AST26XX XDMA engine.
>>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> Reviewed-by: Rob Herring <robh@...nel.org>
>> ---
>> Changes since v2:
>>   - Remove 'sdmc', rename 'vga-mem' to 'memory'
>>
>>   .../devicetree/bindings/soc/aspeed/xdma.txt   | 40 +++++++++++++++++++
>>   MAINTAINERS                                   |  6 +++
>>   2 files changed, 46 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/soc/aspeed/xdma.txt
>>
>> diff --git a/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
>> b/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
>> new file mode 100644
>> index 000000000000..58253ea1587b
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
>> @@ -0,0 +1,40 @@
>> +Aspeed AST25XX and AST26XX XDMA Engine
>> +
>> +The XDMA Engine embedded in the AST2500 and AST2600 SOCs can perform
>> automatic
>> +DMA operations over PCI between the SOC (acting as a BMC) and a host
>> processor.
>> +
>> +Required properties:
>> + - compatible		: must be "aspeed,ast2500-xdma" or
>> +			  "aspeed,ast2600-xdma"
>> + - reg			: contains the address and size of the memory region
>> +			  associated with the XDMA engine registers
>> + - clocks		: clock specifier for the clock associated with the
>> +			  XDMA engine
>> + - resets		: reset specifier for the syscon reset associated with
>> +			  the XDMA engine
>> + - interrupts-extended	: two interrupt cells; the first specifies the
>> global
>> +			  interrupt for the XDMA engine and the second
>> +			  specifies the PCI-E reset or PERST interrupt.
>> + - scu			: a phandle to the syscon node for the system control
>> +			  unit of the SOC
> I think this should be aspeed,scu.


Sure.


>
>> + - memory		: contains the address and size of the memory area to
>> +			  be used by the XDMA engine for DMA operations
> Hmm, I was thinking more like a phandle to a reserved memory region,
> like we have in the aspeed-lpc-ctrl binding.


I think I mentioned before, but that doesn't work with the VGA memory. 
Linux can't reserve it. I haven't quite understood what happens in the 
memory system but I've tried it and it didn't work.


>
>> +
>> +Optional properties:
>> + - pcie-device		: should be either "bmc" or "vga", corresponding to
>> +			  which device should be used by the XDMA engine for
>> +			  DMA operations. If this property is not set, the XDMA
>> +			  engine will use the BMC PCI-E device.
>> +
>> +Example:
>> +
>> +    xdma@...e7000 {
>> +        compatible = "aspeed,ast2500-xdma";
>> +        reg = <0x1e6e7000 0x100>;
>> +        clocks = <&syscon ASPEED_CLK_GATE_BCLK>;
>> +        resets = <&syscon ASPEED_RESET_XDMA>;
>> +        interrupts-extended = <&vic 6>, <&scu_ic
>> ASPEED_AST2500_SCU_IC_PCIE_RESET_LO_TO_HI>;
>> +        scu = <&syscon>;
>> +        pcie-device = "bmc";
>> +        memory = <0x9f000000 0x01000000>;
>> +    };
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index ac9c120d192b..8a14d4268bdc 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -2708,6 +2708,12 @@ S:	Maintained
>>   F:	drivers/media/platform/aspeed-video.c
>>   F:	Documentation/devicetree/bindings/media/aspeed-video.txt
>>   
>> +ASPEED XDMA ENGINE DRIVER
>> +M:	Eddie James <eajames@...ux.ibm.com>
>> +L:	linux-aspeed@...ts.ozlabs.org (moderated for non-subscribers)
>> +S:	Maintained
>> +F:	Documentation/devicetree/bindings/soc/aspeed/xdma.txt
>> +
>>   ASUS NOTEBOOKS AND EEEPC ACPI/WMI EXTRAS DRIVERS
>>   M:	Corentin Chary <corentin.chary@...il.com>
>>   L:	acpi4asus-user@...ts.sourceforge.net
>> -- 
>> 2.24.0
>>
>>