linux-kernel - Re: [PATCH 2/2] PCI/PTM: fix in pci_disable

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Date:   Thu, 7 Jul 2022 20:27:22 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Rajvi Jingar <rajvi.jingar@...ux.intel.com>
Cc:     Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        David Box <david.e.box@...ux.intel.com>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 2/2] PCI/PTM: fix in pci_disable_ptm()

On Thu, Jul 7, 2022 at 7:22 PM Rajvi Jingar
<rajvi.jingar@...ux.intel.com> wrote:
>
> Set ptm_enabled from 'struct pci_dev' to 0 in pci_ptm_disable() to

I would set "Clear" here instead of "Set", but moreover ->

> save the disabled PTM state for the device.
>
> Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power")
> Signed-off-by: Rajvi Jingar <rajvi.jingar@...ux.intel.com>
> ---
>  drivers/pci/pcie/ptm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index 368a254e3124..746e29779c27 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -44,6 +44,7 @@ void pci_disable_ptm(struct pci_dev *dev)
>         pci_read_config_word(dev, ptm + PCI_PTM_CTRL, &ctrl);
>         ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
>         pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
> +       dev->ptm_enabled = 0;

-> I don't think that this is going to work without setting
dev->ptm_enabled in pci_restore_ptm_state() if the restored state
turns out to be "enabled".

>  }
>
>  void pci_save_ptm_state(struct pci_dev *dev)
> --