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Message-ID: <1816071.3jMa2RA6JD@vostro.rjw.lan>
Date: Wed, 22 Apr 2015 03:54:16 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Darren Hart <dvhart@...radead.org>
Cc: ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Zhang Rui <rui.zhang@...el.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / scan: Add a scan handler for PRP0001
On Tuesday, April 14, 2015 03:03:33 PM Rafael J. Wysocki wrote:
> On Tuesday, April 14, 2015 01:50:11 PM Rafael J. Wysocki wrote:
> > On Monday, April 13, 2015 07:04:14 PM Darren Hart wrote:
> > > On Sat, Apr 11, 2015 at 01:28:45AM +0200, Rafael Wysocki wrote:
> > > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > > >
> > > > If the special PRP0001 device ID is present in the given device's list
> > > > of ACPI/PNP IDs and the device has a valid "compatible" property in
> > > > the _DSD, it should be enumerated using the default mechanism,
> > > > unless some scan handlers match the IDs preceding PRP0001 in the
> > > > device's list of ACPI/PNP IDs. In particular, no scan handlers
> > > > matching the IDs following PRP0001 in that list should be attached
> > > > to the device.
> > > >
> > > > To make that happen, define a scan handler that will match PRP0001
> > > > and trigger the default enumeration for the matching devices if the
> > > > "compatible" property is present for them.
> > > >
> > > > Since that requires the check for platform_id and device->handler
> > > > to be removed from acpi_default_enumeration(), move the fallback
> > > > invocation of acpi_default_enumeration() to acpi_bus_attach()
> > > > (after it's checked if there's a matching ACPI driver for the
> > > > device), which is a better place to call it, and do the platform_id
> > > > check in there too (device->handler is guaranteed to be unset at
> > > > the point where the function is looking for a matching ACPI driver).
> > > >
> > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > > > ---
> > > > drivers/acpi/scan.c | 34 +++++++++++++++++++++++++++++-----
> > > > 1 file changed, 29 insertions(+), 5 deletions(-)
> > > >
> > > > Index: linux-pm/drivers/acpi/scan.c
> > > > ===================================================================
> > > > --- linux-pm.orig/drivers/acpi/scan.c
> > > > +++ linux-pm/drivers/acpi/scan.c
> > > > @@ -2390,9 +2390,6 @@ static void acpi_default_enumeration(str
> > > > struct list_head resource_list;
> > > > bool is_spi_i2c_slave = false;
> > > >
> > > > - if (!device->pnp.type.platform_id || device->handler)
> > > > - return;
> > > > -
> > > > /*
> > > > * Do not enemerate SPI/I2C slaves as they will be enuerated by their
> > > > * respective parents.
> > > > @@ -2405,6 +2402,30 @@ static void acpi_default_enumeration(str
> > > > acpi_create_platform_device(device);
> > > > }
> > > >
> > > > +static const struct acpi_device_id generic_device_ids[] = {
> > > > + {"PRP0001", },
> > > > + {"", },
> > > > +};
> > > > +
> > > > +static int acpi_generic_device_attach(struct acpi_device *adev,
> > > > + const struct acpi_device_id *not_used)
> > > > +{
> > > > + /*
> > > > + * Since PRP0001 is the only ID handled here, the test below can be
> > > > + * unconditional.
> > > > + */
> > > > + if (adev->data.of_compatible) {
> > > > + acpi_default_enumeration(adev);
> > > > + return 1;
> > > > + }
> > >
> > > Would a warning be appropriate here? PRP0001 should only appear when paired with
> > > a DSD of GUID Device Properties with a "compatible" entry. If not, it's an
> > > error, correct? I believe we warn on similarly malformed AML?
> >
> > We don't do that as a rule as there would be too many warnings that are not
> > really useful. Users can't do much about those things at this stage (buggy
> > firmware has shipped already) and for the firmware people it is better to
> > cover things like that in firmware test suites (which in theory may help to
> > avoid shipping buggy firmware in the first place).
> >
> > That said we print a warning in acpi_init_of_compatible() if things are not
> > consistent (which doesn't cover the case when _DSD is missing entirely, though),
> > so IMO it'd be better to refine that one instead of adding a new one which
> > wouldn't cover all cases too (eg. if PRP0001 is not the first ID in the list
> > and a previous one is matched to a different scan handler).
>
> Maybe something like the patch below.
Any comments?
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: ACPI / property: Refine consistency check for PRP0001
>
> Refine the check for the presence of the "compatible" property
> if the PRP0001 device ID is present in the device's list of
> ACPI/PNP IDs to also print the message if _DSD is missing
> entirely or the format of it is incorrect.
>
> While at it, reduce the log level of the message to "info"
> and reduce the log level of the "broken _DSD" message to
> "debug" (noise reduction).
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/acpi/property.c | 50 ++++++++++++++++++++++++------------------------
> 1 file changed, 25 insertions(+), 25 deletions(-)
>
> Index: linux-pm/drivers/acpi/property.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/property.c
> +++ linux-pm/drivers/acpi/property.c
> @@ -79,35 +79,15 @@ static bool acpi_properties_format_valid
> static void acpi_init_of_compatible(struct acpi_device *adev)
> {
> const union acpi_object *of_compatible;
> - struct acpi_hardware_id *hwid;
> - bool acpi_of = false;
> int ret;
>
> - /*
> - * Check if the special PRP0001 ACPI ID is present and in that
> - * case we fill in Device Tree compatible properties for this
> - * device.
> - */
> - list_for_each_entry(hwid, &adev->pnp.ids, list) {
> - if (!strcmp(hwid->id, "PRP0001")) {
> - acpi_of = true;
> - break;
> - }
> - }
> -
> - if (!acpi_of)
> - return;
> -
> ret = acpi_dev_get_property_array(adev, "compatible", ACPI_TYPE_STRING,
> &of_compatible);
> if (ret) {
> ret = acpi_dev_get_property(adev, "compatible",
> ACPI_TYPE_STRING, &of_compatible);
> - if (ret) {
> - acpi_handle_warn(adev->handle,
> - "PRP0001 requires compatible property\n");
> + if (ret)
> return;
> - }
> }
> adev->data.of_compatible = of_compatible;
> }
> @@ -115,14 +95,27 @@ static void acpi_init_of_compatible(stru
> void acpi_init_properties(struct acpi_device *adev)
> {
> struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
> + bool acpi_of = false;
> + struct acpi_hardware_id *hwid;
> const union acpi_object *desc;
> acpi_status status;
> int i;
>
> + /*
> + * Check if the special PRP0001 ACPI ID is present and in that case we
> + * fill in Device Tree compatible properties for this device.
> + */
> + list_for_each_entry(hwid, &adev->pnp.ids, list) {
> + if (!strcmp(hwid->id, "PRP0001")) {
> + acpi_of = true;
> + break;
> + }
> + }
> +
> status = acpi_evaluate_object_typed(adev->handle, "_DSD", NULL, &buf,
> ACPI_TYPE_PACKAGE);
> if (ACPI_FAILURE(status))
> - return;
> + goto out;
>
> desc = buf.pointer;
> if (desc->package.count % 2)
> @@ -156,13 +149,20 @@ void acpi_init_properties(struct acpi_de
> adev->data.pointer = buf.pointer;
> adev->data.properties = properties;
>
> - acpi_init_of_compatible(adev);
> - return;
> + if (acpi_of)
> + acpi_init_of_compatible(adev);
> +
> + goto out;
> }
>
> fail:
> - dev_warn(&adev->dev, "Returned _DSD data is not valid, skipping\n");
> + dev_dbg(&adev->dev, "Returned _DSD data is not valid, skipping\n");
> ACPI_FREE(buf.pointer);
> +
> + out:
> + if (acpi_of && !adev->data.of_compatible)
> + acpi_handle_info(adev->handle,
> + "PRP0001 requires 'compatible' property\n");
> }
>
> void acpi_free_properties(struct acpi_device *adev)
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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