linux-kernel - RE: [PATCH v2] PCI: Disable LTR on suspend for SSSTC 0x9100

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Date:   Fri, 18 Mar 2022 11:30:31 +0000
From:   "Huang, Patrick" <Patrick.Huang@....com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] PCI: Disable LTR on suspend for SSSTC 0x9100

[AMD Official Use Only]

Hi all,
After retrying suspend with this patch, get suspend test successfully and run over 1800 cycles
I think that is test environment error before.
Thanks

Best Regard,
Patrick
-----Original Message-----
From: Limonciello, Mario <Mario.Limonciello@....com> 
Sent: Friday, March 18, 2022 10:43 AM
To: Bjorn Helgaas <bhelgaas@...gle.com>; open list:PCI SUBSYSTEM <linux-pci@...r.kernel.org>; open list <linux-kernel@...r.kernel.org>; Huang, Patrick <Patrick.Huang@....com>
Subject: Re: [PATCH v2] PCI: Disable LTR on suspend for SSSTC 0x9100

+Patrick Huang

On 3/17/22 08:10, Mario Limonciello wrote:
> Some drives from SSSTC are showing stability problems after s0i3 entry 
> when the Linux kernel is in s2idle loop if LTR has been enabled. This 
> leads to failures to resume.
> 
> This appears to be a firmware issue specific to SSSTC SSDs, so quirk 
> them to avoid LTR being enabled during the suspend process.
> 
> Link: 
> https://lore.kernel.org/linux-nvme/20220315072233.GA2288@lst.de/T/#mb9
> b5782220a32e2c69fe37cf04ae1501b0f48221
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> changes from v1->v2:
>   * Move into a PCI quirk, handle entirely in PCI subsystem
> 

Patrick has been running stress tests with this patch and reported a failure.  When it's figured out we will re-submit V3.

If any concerns to this approach in V2 though, comments still welcome.

Thanks,

>   drivers/pci/quirks.c    | 17 +++++++++++++++++
>   include/linux/pci_ids.h |  2 ++
>   2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 
> d2dd6a6cda60..005142d574e7 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5879,3 +5879,20 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1533, rom_bar_overlap_defect);
>   DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1536, rom_bar_overlap_defect);
>   DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1537, rom_bar_overlap_defect);
>   DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1538, 
> rom_bar_overlap_defect);
> +
> +/*
> + * SSSTC firmware will continue to send LTR requests after device has 
> +entered D3
> + *
> + * This behavior causes problems when entering/exit s2idle, so avoid 
> +letting LTR
> + * be enabled during suspend.
> + */
> +static void ssstc_disable_ltr(struct pci_dev *pdev) {
> +	pcie_capability_clear_word(pdev, PCI_EXP_DEVCTL2, 
> +PCI_EXP_DEVCTL2_LTR_EN); } static void ssstc_enable_ltr(struct 
> +pci_dev *pdev) {
> +	pcie_capability_set_word(pdev, PCI_EXP_DEVCTL2, 
> +PCI_EXP_DEVCTL2_LTR_EN); } 
> +DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_SSSTC, 0x9100, 
> +ssstc_disable_ltr); DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_SSSTC, 
> +0x9100, ssstc_enable_ltr);
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h index 
> 130949c3b486..ab47ccdd2ece 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -2568,6 +2568,8 @@
>   #define PCI_VENDOR_ID_TEKRAM		0x1de1
>   #define PCI_DEVICE_ID_TEKRAM_DC290	0xdc29
>   
> +#define PCI_VENDOR_ID_SSSTC		0x1e95
> +
>   #define PCI_VENDOR_ID_TEHUTI		0x1fc9
>   #define PCI_DEVICE_ID_TEHUTI_3009	0x3009
>   #define PCI_DEVICE_ID_TEHUTI_3010	0x3010