linux-kernel - Re: [PATCH] misc: sram: extend usage of reserved partitions

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Date:	Mon, 10 Aug 2015 13:47:04 +0300
From:	Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Philipp Zabel <p.zabel@...gutronix.de>,
	Heiko Stübner <heiko@...ech.de>,
	Arnd Bergmann <arnd@...db.de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] misc: sram: extend usage of reserved partitions

Hi Greg,

On 10.08.2015 06:27, Greg Kroah-Hartman wrote:
> On Mon, Aug 10, 2015 at 12:40:02AM +0300, Vladimir Zapolskiy wrote:
>> This change adds functionality to operate on reserved SRAM partitions
>> described in device tree file. Two partition properties are added,
>> "pool" and "export", the first one allows to share a specific partition
>> for usage by a kernel consumer in the same manner as it is done for
>> the whole SRAM device, and "export" property provides access to some
>> SRAM area from userspace over sysfs interface. Practically it is
>> possible to specify both properties for an SRAM partition, however
>> simultaneous access from a kernel consumer and from userspace is not
>> serialized, but still the combination may be useful for debugging
>> purpose.
>>
>> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
>> ---
>> To test SRAM partition export to userspace it might be sufficient
>> to add an exported subnode, write data to created binary attribute file,
>> do soft reboot and read the contents of the same binary attribute
>> file. Aware of any potential use of SRAM by a bootloader etc.
>>
>> To give an idea how to use "pool" partition feature here is an example
>> for Freescale iMX6Q SabreAuto with CODA driver as a user:
>>
>> arch/arm/boot/dts/imx6q.dtsi @@ -82,6 +82,10 @@
>>  			compatible = "mmio-sram";
>>  			reg = <0x00900000 0x40000>;
>>  			clocks = <&clks IMX6QDL_CLK_OCRAM>;
>> +
>> +			#address-cells = <1>;
>> +			#size-cells = <1>;
>> +			ranges = <0 0x00900000 0x40000>;
>>  		};
>>  
>>  		aips-bus@...00000 { /* AIPS1 */
>> arch/arm/boot/dts/imx6qdl-sabreauto.dtsi @@ -490,3 +490,18 @@
>>  				0x0000c000 0x1404a38e 0x00000000>;
>>  	};
>>  };
>> +
>> +&ocram {
>> +	#address-cells = <1>;
>> +	#size-cells = <1>;
>> +
>> +	vpu_iram: vpu_iram {
>> +		reg = <0x00008000 0x00021000>;
>> +		pool;
>> +	};
>> +};
>> +
>> +&vpu {
>> +	iram = <&vpu_iram>;
>> +};
>>
> 
> Putting a diff in a patch changelog is tricky, do you really need it?

you are right, it is tricky, that's why this is actually not a valid
diff, I tested on my environment and the email can be applied with git-am.

> And why send 2 copies of this patch, what changed?
> 
> confused,
> 

sorry for confusion, occasionally I gave two same files to
git-send-email. The versions are absolutely identical, please ignore one
of them.

With best wishes,
Vladimir

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