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Date: Thu, 17 Feb 2022 10:11:55 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: sylv <sylv@...v.io>, Jean Delvare <jdelvare@...e.com>,
Jonathan Corbet <corbet@....net>
Cc: linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
Patrick Rudolph <patrick.rudolph@...ements.com>,
linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/3] hwmon (xdpe12284): Add support for xdpe11280
On 2/17/22 08:39, sylv wrote:
> On Thu, 2022-02-17 at 07:20 -0800, Guenter Roeck wrote:
>> On 2/17/22 06:41, Marcello Sylvester Bauer wrote:
>>> Add support for another family of Infineon Multi-phase controllers.
>>> The xdpe11280 uses linear instead of vid data format for VOUT.
>>> Add the required logic to detect VOUT_MODE during identification,
>>> and set the format accordingly.
>>>
>> This talks about the chip, but ...
>
> Oh, sure. I should be more clear that it is a chip of a different
> family.
>
>>
>>> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
>>> ---
>>> Documentation/hwmon/xdpe12284.rst | 10 +++++++---
>>> drivers/hwmon/pmbus/xdpe12284.c | 17 ++++++++++++++++-
>>> 2 files changed, 23 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/Documentation/hwmon/xdpe12284.rst
>>> b/Documentation/hwmon/xdpe12284.rst
>>> index 67d1f87808e5..e9a5a19b0c3d 100644
>>> --- a/Documentation/hwmon/xdpe12284.rst
>>> +++ b/Documentation/hwmon/xdpe12284.rst
>>> @@ -5,6 +5,10 @@ Kernel driver xdpe122
>>>
>>> Supported chips:
>>>
>>> + * Infineon XDPE11280
>>> +
>>> + Prefix: 'xdpe11280'
>>> +
>>> * Infineon XDPE12254
>>>
>>> Prefix: 'xdpe12254'
>>> @@ -20,9 +24,9 @@ Authors:
>>> Description
>>> -----------
>>>
>>> -This driver implements support for Infineon Multi-phase XDPE122
>>> family
>>> -dual loop voltage regulators.
>>> -The family includes XDPE12284 and XDPE12254 devices.
>>> +This driver implements support for Infineon Multi-phase XDPE112
>>> and XDPE122
>>> +family dual loop voltage regulators.
>>> +These families include XDPE11280, XDPE12284 and XDPE12254 devices.
>>> The devices from this family complaint with:
>>
>> Hmm, s/complaint/compliant/.
>
> ack
>
>>
>> Anyway, is it still correct that the XDPE11280 is compliant with the
>> Intel specifications ? The datasheet isn't public, so I can not check
>> myself
>> what the chip actually supports.
>
> The hardware we are testing on is an Intel Cascade Lake, which uses
> this chip. The datasheet tells us it is compliant:
>
> ```
> The XDPE11280B implements a fully compliant Intel® VR 13, VR12, VR
> 12.5, VR13.HC, and IMVP8 Serial VID (SVID)
> interface.
> ```
>
This seems to be one of those chips where the vendor doesn't even admit
that it exists unless one signs an NDA. Sigh :-(.
>>
>>>
>>> - Intel VR13 and VR13HC rev 1.3, IMVP8 rev 1.2 and IMPVP9 rev 1.3
>>> DC-DC
>>> diff --git a/drivers/hwmon/pmbus/xdpe12284.c
>>> b/drivers/hwmon/pmbus/xdpe12284.c
>>> index b07da06a40c9..ec947c697670 100644
>>> --- a/drivers/hwmon/pmbus/xdpe12284.c
>>> +++ b/drivers/hwmon/pmbus/xdpe12284.c
>>> @@ -27,6 +27,9 @@ static int xdpe122_read_word_data(struct
>>> i2c_client *client, int page,
>>> s32 mantissa;
>>> int ret;
>>>
>>> + if (info->format[PSC_VOLTAGE_OUT] == linear)
>>> + return -ENODATA;
>>> +
>>> switch (reg) {
>>> case PMBUS_VOUT_OV_FAULT_LIMIT:
>>> case PMBUS_VOUT_UV_FAULT_LIMIT:
>>> @@ -75,9 +78,19 @@ static int xdpe122_read_word_data(struct
>>> i2c_client *client, int page,
>>> static int xdpe122_identify(struct i2c_client *client,
>>> struct pmbus_driver_info *info)
>>> {
>>> - u8 vout_params;
>>> + u8 vout_mode, vout_params;
>>> int i, ret;
>>>
>>> + ret = pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + vout_mode = ret >> 5;
>>> + if (vout_mode == 0) {
>>> + info->format[PSC_VOLTAGE_OUT] = linear;
>>> + return 0;
>>> + }
>>
>> .... the code above is not chip dependent but this code checks the
>> mode register on page 0. At the very least this is confusing.
>>
>> What the driver should do instead is to check the chip type during
>> probe and make the necessary changes there, ie set the output format
>> for xdpe11280 to linear and drop the pointers to the .identify
>> and .read_word_data.
>
> Sgtm. This sounds like a better approach indeed.
>
That makes me wonder if the chip needs to be added to this driver in the first
place, or if it could be added to pmbus.c instead. Any idea ?
Thanks,
Guenter
> Thanks,
> Marcello
>
>>
>> Guenter
>>
>>> +
>>> for (i = 0; i < XDPE122_PAGE_NUM; i++) {
>>> /* Read the register with VOUT scaling value.*/
>>> ret = pmbus_read_byte_data(client, i,
>>> PMBUS_VOUT_MODE);
>>> @@ -140,6 +153,7 @@ static int xdpe122_probe(struct i2c_client
>>> *client)
>>> }
>>>
>>> static const struct i2c_device_id xdpe122_id[] = {
>>> + {"xdpe11280", 0},
>>> {"xdpe12254", 0},
>>> {"xdpe12284", 0},
>>> {}
>>> @@ -148,6 +162,7 @@ static const struct i2c_device_id xdpe122_id[]
>>> = {
>>> MODULE_DEVICE_TABLE(i2c, xdpe122_id);
>>>
>>> static const struct of_device_id __maybe_unused
>>> xdpe122_of_match[] = {
>>> + {.compatible = "infineon,xdpe11280"},
>>> {.compatible = "infineon,xdpe12254"},
>>> {.compatible = "infineon,xdpe12284"},
>>> {}
>>
>
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