Re: [V2 PATCH 1/5] ACPI / scan: Parse _CCA and setup device coherency

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On 5/6/2015 5:21 PM, Rafael J. Wysocki wrote:
> >>+	bool
> >>+
> >>+config ACPI_SUPPORT_CCA_ZERO
> >
> >I guess this means "we support devices that can DMA, but are not coherent".
> >right?
>
>Yes, basically when _CCA=0.
So what about

	ARCH_SUPPORT_CACHE_INCOHERENT_DMA

Since this is specific to ACPI _CCA, I just want to be clear with the naming.

or something similar?

> >>+	bool
> >>+
> >>   config ACPI_SLEEP
> >>   	bool
> >>   	depends on SUSPEND || HIBERNATION
> >>diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
> >>index 4bf7559..a6feca4 100644
> >>--- a/drivers/acpi/acpi_platform.c
> >>+++ b/drivers/acpi/acpi_platform.c
> >>@@ -108,9 +108,11 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev)
> >>   	if (IS_ERR(pdev))
> >>   		dev_err(&adev->dev, "platform device creation failed: %ld\n",
> >>   			PTR_ERR(pdev));
> >>-	else
> >>+	else {
> >
> >Please add braces to both branches when making such changes (as per CodingStyle).
> >
>
>OK.
>
> >>+		acpi_setup_device_dma(adev, &pdev->dev);
> >
> >Why do we need to do that here (for the second time)?
>
>Because we are calling:
>    acpi_create_platform_device()
>      |--> platform_device_register_device_full()
>        |-->platform_device_alloc()
>
>This creates platform_device, which allocate a new platform_device->dev.
>This is not the same as the original acpi_device->dev that was created
>during acpi_add_single_object(). So, we have to set up the device
>coherency again.
Ah, so the second arg is different now.

Well, in that case, why do we need to set it up for the adev's dev member?


Just for sanity, since I don't know if adev->dev will be referenced anywhere else. This way, it's consistent for all copied of struct device generated.

Lemme know if you think that is unnecessary.

Thanks,

Suravee


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