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Date: Mon, 4 Dec 2017 16:41:45 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Hans de Goede <hdegoede@...hat.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
On 04/12/17 16:33, Hans de Goede wrote:
> 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?
dep_unmet predates device links, but now we have device links, they are
better anyway.
>
> 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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