linux-kernel - Re: [PATCH 1/2] ahci: Add Green Sardine vendor ID as board_ahci

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Date:   Tue, 15 Feb 2022 08:05:50 +0100
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Mario Limonciello <Mario.Limonciello@....com>,
        Hans de Goede <hdegoede@...hat.com>
Cc:     linux-ide@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Nehal-bakulchandra Shah <Nehal-bakulchandra.Shah@....com>
Subject: Re: [PATCH 1/2] ahci: Add Green Sardine vendor ID as
 board_ahci_mobile

Dear Mario,


Am 14.02.22 um 17:07 schrieb Limonciello, Mario:

> +Hans
> 
>> (For the records, is part of Linux since 5.16-rc2 (commit 1527f69204fe).)
>>
>> Am 12.11.21 um 21:15 schrieb Mario Limonciello:
>>> AMD requires that the SATA controller be configured for devsleep in order
>>> for S0i3 entry to work properly.
>>>
>>> commit b1a9585cc396 ("ata: ahci: Enable DEVSLP by default on x86 with
>>> SLP_S0") sets up a kernel policy to enable devsleep on Intel mobile
>>> platforms that are using s0ix.  Add the PCI ID for the SATA controller in
>>> Green Sardine platforms to extend this policy by default for AMD based
>>> systems using s0i3 as well.
>>>
>>> Cc: Nehal-bakulchandra Shah <Nehal-bakulchandra.Shah@....com>
>>> BugLink:
>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugz
>> illa.kernel.org%2Fshow_bug.cgi%3Fid%3D214091&amp;data=04%7C01%7Cm
>> ario.limonciello%40amd.com%7Ca32a202d437544cd2cbb08d9ef9112c0%7C3d
>> d8961fe4884e608e11a82d994e183d%7C0%7C0%7C637804228648002522%7CU
>> nknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI
>> 6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=CbfImBnwc8uV1L5QRBuV
>> PLkP72wpS9yif1UbUwykhNI%3D&amp;reserved=0

You have to love Microsoft Outlook.

>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>> ---
>>>    drivers/ata/ahci.c | 1 +
>>>    1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
>>> index d60f34718b5d..1e1167e725a4 100644
>>> --- a/drivers/ata/ahci.c
>>> +++ b/drivers/ata/ahci.c
>>> @@ -438,6 +438,7 @@ static const struct pci_device_id ahci_pci_tbl[] = {
>>>    	/* AMD */
>>>    	{ PCI_VDEVICE(AMD, 0x7800), board_ahci }, /* AMD Hudson-2 */
>>>    	{ PCI_VDEVICE(AMD, 0x7900), board_ahci }, /* AMD CZ */
>>> +	{ PCI_VDEVICE(AMD, 0x7901), board_ahci_mobile }, /* AMD Green Sardine */
>>
>> Aren't 0x7900 and 0x7901 the same device only in different modes? I
>> wonder, why different boards and different comments are used.
> 
> No they aren't the same device in different modes.
> 
> Reference:
> https://www.amd.com/en/support/tech-docs/processor-programming-reference-ppr-for-amd-family-19h-model-51h-revision-a1
> Page 33 has a table.

That table misses 0x7900h. (Where can I find it?) coreboot has 0x7900 
defined for Cezanne:

     src/include/device/pci_ids.h:#define PCI_DEVICE_ID_AMD_CZ_SATA  0x7900
     src/soc/amd/stoneyridge/include/soc/pci_devs.h: * SATA_IDE_IDEVID 
              0x7900

The PCI database too [3]:

> FCH SATA Controller [IDE mode]


>> Additionally, the device 0x7901 is also present in desktop systems like
>> Dell OptiPlex 5055 and MSI B350 MORTAR. Is `board_ahci_mobile` the right
>> board then? Or should the flag `AHCI_HFLAG_IS_MOBILE` be renamed to
>> avoid confusion?
> 
> Are you having a problem or just want clarity in the enum definition?

It’s more about clarity, and understanding the two different entries.

> This was introduced by Hans in commit ebb82e3c79d2a to set LPM policy properly
> for a number of mobile devices.
> 
> My opinion here is that the policy being for "mobile" devices only is short sighted as power
> consumption policy on desktops is also relevant as OEMs ship desktops that need to meet
> various power regulations for those too.
> 
> So I would be in the camp for renaming the flags.

Why can’t the LPM policy, if available(?), not be set for `board_ahci` 
by default, so `board_ahci_mobile` could be removed?

>>>    	/* AMD is using RAID class only for ahci controllers */
>>>    	{ PCI_VENDOR_ID_AMD, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>>>    	  PCI_CLASS_STORAGE_RAID << 8, 0xffffff, board_ahci },


Kind regards,

Paul


[1]: https://review.coreboot.org/10418
[2]: https://review.coreboot.org/20200
[3]: https://pci-ids.ucw.cz/read/PC/1022/7900