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Date: Mon, 4 Dec 2017 15:33:29 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Adrian Hunter <adrian.hunter@...el.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
Carlo Caione <carlo@...lessm.com>
Subject: Re: [PATCH] ACPI / LPSS: Add device link for CHT SD card dependency
on I2C
Hi,
On 04-12-17 15:30, Adrian Hunter wrote:
> On 04/12/17 15:48, Hans de Goede wrote:
>> Hi,
>>
>> Wouldn't it be easier to use the ACPI _DEP tracking for this, e.g.
>
> It is using _DEP, see acpi_lpss_dep()
>
>> add something like this to the the probe function:
>>
>> struct acpi_device = ACPI_COMPANION(device);
>>
>> if (acpi_device->dep_unmet)
>> return -EPROBE_DEFER;
>>
>> No idea if this will work, but if it does work, using the deps described
>> in the ACPI tables seems like a better solution then hardcoding this.
>
> That would not work because there are other devices listed in the _DEP
> method so dep_unmet is always true. So we are left checking _DEP but only
> for specific device dependencies.
Ugh, understood thank you for explaining this. Perhaps it is a good idea
to mention in the commit message why acpi_dev->dep_unmet cannot be used
here?
Regards,
Hans
>> On 04-12-17 13:32, Adrian Hunter wrote:
>>> Some Cherry Trail boards have a dependency between the SDHCI host
>>> controller used for SD cards and an external PMIC accessed via I2C. Add a
>>> device link between the SDHCI host controller (consumer) and the I2C
>>> adapter (supplier).
>>>
>>> This patch depends on a fix to devices links, namely commit 0ff26c662d5f
>>> ("driver core: Fix device link deferred probe"). And also either,
>>> commit 126dbc6b49c8 ("PM: i2c-designware-platdrv: Clean up PM handling in
>>> probe"), or patch "PM / runtime: Fix handling of suppliers with disabled
>>> runtime PM".
>>>
>>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>>> ---
>>> drivers/acpi/acpi_lpss.c | 139
>>> +++++++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 139 insertions(+)
>>>
>>> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
>>> index 7f2b02cc8ea1..9d82f2f6c327 100644
>>> --- a/drivers/acpi/acpi_lpss.c
>>> +++ b/drivers/acpi/acpi_lpss.c
>>> @@ -290,6 +290,11 @@ static void bsw_pwm_setup(struct lpss_private_data
>>> *pdata)
>>> {}
>>> };
>>> +static const struct x86_cpu_id cht_cpu[] = {
>>> + ICPU(INTEL_FAM6_ATOM_AIRMONT), /* Braswell, Cherry Trail */
>>> + {}
>>> +};
>>> +
>>> #else
>>> #define LPSS_ADDR(desc) (0UL)
>>> @@ -427,6 +432,139 @@ static int register_device_clock(struct acpi_device
>>> *adev,
>>> return 0;
>>> }
>>> +struct lpss_device_links {
>>> + const char *supplier_hid;
>>> + const char *supplier_uid;
>>> + const char *consumer_hid;
>>> + const char *consumer_uid;
>>> + const struct x86_cpu_id *cpus;
>>> + u32 flags;
>>> +};
>>> +
>>> +static const struct lpss_device_links lpss_device_links[] = {
>>> + {"808622C1", "7", "80860F14", "3", cht_cpu, DL_FLAG_PM_RUNTIME},
>>> +};
>>> +
>>> +static bool hid_uid_match(const char *hid1, const char *uid1,
>>> + const char *hid2, const char *uid2)
>>> +{
>>> + return !strcmp(hid1, hid2) && uid1 && uid2 && !strcmp(uid1, uid2);
>>> +}
>>> +
>>> +static bool acpi_lpss_is_supplier(struct acpi_device *adev,
>>> + const struct lpss_device_links *link)
>>> +{
>>> + return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
>>> + link->supplier_hid, link->supplier_uid);
>>> +}
>>> +
>>> +static bool acpi_lpss_is_consumer(struct acpi_device *adev,
>>> + const struct lpss_device_links *link)
>>> +{
>>> + return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
>>> + link->consumer_hid, link->consumer_uid);
>>> +}
>>> +
>>> +struct hid_uid {
>>> + const char *hid;
>>> + const char *uid;
>>> +};
>>> +
>>> +static int match_hid_uid(struct device *dev, void *data)
>>> +{
>>> + struct acpi_device *adev = ACPI_COMPANION(dev);
>>> + struct hid_uid *id = data;
>>> +
>>> + if (!adev)
>>> + return 0;
>>> +
>>> + return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
>>> + id->hid, id->uid);
>>> +}
>>> +
>>> +static struct device *acpi_lpss_find_device(const char *hid, const char
>>> *uid)
>>> +{
>>> + struct hid_uid data = {
>>> + .hid = hid,
>>> + .uid = uid,
>>> + };
>>> +
>>> + return bus_find_device(&platform_bus_type, NULL, &data, match_hid_uid);
>>> +}
>>> +
>>> +static bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle handle)
>>> +{
>>> + struct acpi_handle_list dep_devices;
>>> + acpi_status status;
>>> + int i;
>>> +
>>> + if (!acpi_has_method(adev->handle, "_DEP"))
>>> + return false;
>>> +
>>> + status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
>>> + &dep_devices);
>>> + if (ACPI_FAILURE(status)) {
>>> + dev_dbg(&adev->dev, "Failed to evaluate _DEP.\n");
>>> + return false;
>>> + }
>>> +
>>> + for (i = 0; i < dep_devices.count; i++) {
>>> + if (dep_devices.handles[i] == handle)
>>> + return true;
>>> + }
>>> +
>>> + return false;
>>> +}
>>> +
>>> +static void acpi_lpss_link_consumer(struct device *dev1,
>>> + const struct lpss_device_links *link)
>>> +{
>>> + struct device *dev2;
>>> +
>>> + dev2 = acpi_lpss_find_device(link->consumer_hid, link->consumer_uid);
>>> + if (!dev2)
>>> + return;
>>> +
>>> + if (acpi_lpss_dep(ACPI_COMPANION(dev2), ACPI_HANDLE(dev1)))
>>> + device_link_add(dev2, dev1, link->flags);
>>> +
>>> + put_device(dev2);
>>> +}
>>> +
>>> +static void acpi_lpss_link_supplier(struct device *dev1,
>>> + const struct lpss_device_links *link)
>>> +{
>>> + struct device *dev2;
>>> +
>>> + dev2 = acpi_lpss_find_device(link->supplier_hid, link->supplier_uid);
>>> + if (!dev2)
>>> + return;
>>> +
>>> + if (acpi_lpss_dep(ACPI_COMPANION(dev1), ACPI_HANDLE(dev2)))
>>> + device_link_add(dev1, dev2, link->flags);
>>> +
>>> + put_device(dev2);
>>> +}
>>> +
>>> +static void acpi_lpss_create_device_links(struct acpi_device *adev,
>>> + struct platform_device *pdev)
>>> +{
>>> + int i;
>>> +
>>> + for (i = 0; i < ARRAY_SIZE(lpss_device_links); i++) {
>>> + const struct lpss_device_links *link = &lpss_device_links[i];
>>> +
>>> + if (link->cpus && !x86_match_cpu(link->cpus))
>>> + continue;
>>> +
>>> + if (acpi_lpss_is_supplier(adev, link))
>>> + acpi_lpss_link_consumer(&pdev->dev, link);
>>> +
>>> + if (acpi_lpss_is_consumer(adev, link))
>>> + acpi_lpss_link_supplier(&pdev->dev, link);
>>> + }
>>> +}
>>> +
>>> static int acpi_lpss_create_device(struct acpi_device *adev,
>>> const struct acpi_device_id *id)
>>> {
>>> @@ -500,6 +638,7 @@ static int acpi_lpss_create_device(struct acpi_device
>>> *adev,
>>> adev->driver_data = pdata;
>>> pdev = acpi_create_platform_device(adev, dev_desc->properties);
>>> if (!IS_ERR_OR_NULL(pdev)) {
>>> + acpi_lpss_create_device_links(adev, pdev);
>>> return 1;
>>> }
>>>
>>
>
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