Hi,
On Wed, Oct 28, 2015 at 4:01 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> On Tue, Oct 27, 2015 at 02:11:11PM -0700, Dustin Byford wrote:
>> Hi Mika,
>>
>> On Fri Oct 23 11:20, Mika Westerberg wrote:
>>
>> > You should either use proper _HID/_CID for the device or put "PRP0001"
>> > to the _HID and let the match happen with DT .compatible strings. I've
>> > attached a hack that I use locally.
>>
>> I have a similar hack over here. I have a question though:
>>
>> > The corresponding ASL fragment would look like:
>> >
>> >
>> > Device (AT24)
>> > {
>> > Name (_HID, "PRP0001")
>> >
>> > Method (_CRS, 0, Serialized) {
>> > Name (UBUF, ResourceTemplate () {
>> > I2cSerialBus (0x50, ControllerInitiated, 0x00061A80,
>> > AddressingMode7Bit, "\\_SB.I2C6",
>> > 0x00, ResourceConsumer)
>> > })
>> > Return (UBUF)
>> > }
>> >
>> > Name (_DSD, Package () {
>> > ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
>> > Package () {
>> > Package () {"compatible", "atmel,24c02"},
>>
>> The "c02" in 24c02 also indicates the size. I've always found it a
>> little awkward when you could have a compatible string that disagrees
>> with firmware properties. Should we do something about that?
>>
>> For example, is the more generic string, "atmel,at24" better? I'm not
>> sure I like that approach in general, but it works well for the at24
>> devices. at25 does it the same way.
>
> I think DT version actually identifies this if the device node is called
> "at24". I'm not sure if we can do that with ACPI though.
>
> I agree that we could use "atmel,at24" here but that requires
> corresponding binding to be added to
> Documentation/devicetree/bindings/i2c/trivial-devices.txt and review
> from DT folks. Definitely worth doing.
It looks like you are supposed to have the first compatible entry be
the exact manufacturer,model.
http://devicetree.org/Device_Tree_Usage#Understanding_the_compatible_Property
I am considering using a generic compatible entry ("linux,at24") to
match the Linux at24 driver.
In my case, I'm using a M24C02 from ST, so the compatible line would be:
Package () {"compatible", Package () {"st,m24c02", "linux,at24"}},
Package () {"size", 256},
Package () {"pagesize", 16},
The "linux,at24" would require the other properties (size and
pagesize) to be present.
I've seen something similar done with a few other devices.
> Alternatively we may use the same _HID "INT3499" as Andy is doing in his
> series with the below properties.
The only issue with reusing INT3499 is that it is configured to be a
24C08 in the at24 driver.
Reusing the 24C08 HID for a 24C02 or other chip might be a bit confusing.
Ben
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