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132 lines
4.5 KiB
Markdown
132 lines
4.5 KiB
Markdown
# Fixing Trackpads: Manual
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* [Checking GPI0](#checking-gpio)
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* [Edits to the sample SSDT](#edits-to-the-sample-ssdt)
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* [Compiling the SSDT](#compiling-the-ssdt)
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* [Wrapping up](#wrapping-up)
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## Checking GPI0
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The first thing which should be checked is the GPI0 device, which is required for VoodooI2C. The best way to check this is working is to use IORegistryViewer.
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![]()
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Here, we can see that VoodooI2C is attached to GPI0 so no edits are needed for GPI0 and you can skip to the next section.
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If VoodooI2C isn't attached, then you may need to modify the `_STA` method in the `GPI0` device. In that case, you will need to find the GPI0 device in ACPI.
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First open your decompiled DSDT you got from [Dumping the DSDT](/Manual/dump.md) and [Decompiling and Compiling](/Manual/compile.md) with either maciASL(if in macOS) or any other text editor if in Windows or Linux(VSCode has an [ACPI extension](https://marketplace.visualstudio.com/items?itemName=Thog.vscode-asl) that can also help).
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Next search for `Device (GPI0)`. Should give you a result similar to this:
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We can see that `_STA` method, which enables or disable the GPI0 device:
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```
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Method (_STA, 0, NotSerialized)
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{
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If ((SBRG == Zero))
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{
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Return (Zero)
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}
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If ((GPEN == Zero))
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{
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Return (Zero)
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}
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Return (0x0F)
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}
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```
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We want the value returned from _STA to be 0x0F, as 0x00 (Zero) would disable the device. `_STA` currently checks both `SBRG` and `GPEN`. If either `SBRG` or `GPEN` is equal to zero, then zero will be returned. Generally, `SBRG` should not be modified, as modifying it can break the `GPI0` device. Only modify the `GPEN` value if you need to enable the `GPI0` device.
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Here's some more examples:
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What we care about from this is the `_STA` method:
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```
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Method (_STA, 0, NotSerialized)
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{
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If ((GPHD == One))
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{
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Return (0x03)
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}
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Return (0x0F)
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}
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```
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What we want is for this to always return `0x0F` when booting macOS, so we want to make an SSDT that will return `GPHD == Zero` in macOS.
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**NOTE that you may have the other way around where GPHD needs to be set as `One` to return `0x0F`**. And your device name may also be different, don't throw random SSDTs in thinking it'll work
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## Edits to the sample SSDT
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Now that we have our ACPI path, lets grab our SSDT and get to work:
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* [SSDT-GPI0.dsl](https://github.com/dortania/Getting-Started-With-ACPI/blob/master/extra-files/decompiled/SSDT-GPI0.dsl)
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From the first example, we'll want to set GPEN to `One` to allow it to operate in macOS:
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```
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If (_OSI ("Darwin"))
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{
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GPEN = One <- Proper variables
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}
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```
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You will want to test the SSDT at this point by [compiling the SSDT!](/Manual/compile.md) and adding it to your config.plist. VoodooI2C should now be attached to the GPI0 device as shown at the top of the GPI0 section.
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## Enabling Trackpad
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Often times, the I2C devices check to see if they are running in Windows before enabling themselves. Similarly to the `GPI0` device, these devices contain a `_STA` method. For example, this is the I2C1 device below:
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The part we care about is the `_STA` method:
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```
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Method (_STA, 0, NotSerialized) // _STA: Status
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{
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Return (LSTA (SMD1))
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}
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```
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In this case, `_STA` is referring to another method, `LSTA`. If we search for `Method (LSTA`, we'll see the below:
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```
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Method (LSTA, 1, Serialized)
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{
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If (((Arg0 == 0x00) || (Arg0 == 0x03)))
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{
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Return (0x00)
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}
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If (CondRefOf (OSYS))
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{
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If ((OSYS < 0x07DC))
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{
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Return (0x00)
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}
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}
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Return (0x0F)
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}
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```
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`LSTA` checks `Arg0` and `OSYS`. `Arg0` is the value passed in from where it's called. In this example, `_STA` passes in `SMD1` as Arg0. This value should already be correct. The value which we should check is `OSYS`, which is a value which stores information about the current OS running. We will want to look for any place in which `OSYS` is set (`OSYS = 0x07DC` for example). In this DSDT, this is set under `\_SB.PCI0._INI` as shown below:
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![]()
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There are various checks for many different versions of Windows, but there is no check for `Darwin`. We generally want to set `OSYS` to the value for the latest version of Windows in order to enable the most capabilities.
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## Wrapping up
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Once you're done making your SSDT, either head to the next page to finish the rest of the SSDTs or head here if you're ready to wrap up:
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* [**Cleanup**](/cleanup.md)
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