linux-kernel - Re: [PATCH V2] ACPI / LPSS: Add device link for CHT SD card dependency on I2C

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Date:   Fri, 15 Dec 2017 14:00:31 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Carlo Caione <carlo@...lessm.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH V2] ACPI / LPSS: Add device link for CHT SD card
 dependency on I2C

On 15/12/17 11:10, Adrian Hunter wrote:
> On 14/12/17 16:16, Andy Shevchenko wrote:
>> On Thu, 2017-12-07 at 11:03 +0200, 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".
>>>
>>
>> Fine with me, though I think below comment worth to address.
>>
>>>  
>>> +static const struct x86_cpu_id cht_cpu[] = {
>>> +	ICPU(INTEL_FAM6_ATOM_AIRMONT),	/* Braswell, Cherry
>>> Trail */
>>> +	{}
>>> +};
>>
>> I would rather to modify ICPU() macro to accept driver data where we
>> just pass an unsigned long value to be assigned as lpss_quirks and
>> introduce another quirk.
>>
>>> +
>>> +		if (link->cpus && !x86_match_cpu(link->cpus))
>>> +			continue;
>>
>> ...thus, 
>>
>> if (!(lpss_quirks & LPSS_QUIRK_NEED_DEVICE_LINKS))
>>  continue;
> 
> The intention is to associate the cpu with the link information i.e. that
> link is needed on that cpu.  What you are proposing is slightly different.
> 

Spoke with Andy and decided the cpu check could be removed altogether for
now, so I will send a V3 shortly.