[+cc Rafael, Pavel, linux-pm]
On Wed, Jan 14, 2015 at 09:36:48PM -0800, Yinghai Lu wrote:
> Wilmer reported continuous suspend/resume does not work after
> commit 928bea964827 ("PCI: Delay enabling bridges until they're needed").
>
> For pci bridge without driver, FW enable it already.
> In pci_pm_resume/pci_pm_reenable_device after first resume
> will not reenable the device, aka the status is not the same
> as that before first suspend.
>
> Try to update enable status according to register value before
> calling pci_reenable_device, so we will not miss those pm
> operation calling for next suspend/resume.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=86421
> Fixes: 928bea964827 ("PCI: Delay enabling bridges until they're needed")
> Reported-by: Wilmer van der Gaast <kernel@xxxxxxxxxxxxxxxx>
> Bisected-by: Wilmer van der Gaast <kernel@xxxxxxxxxxxxxxxx>
> Tested-by: Wilmer van der Gaast <kernel@xxxxxxxxxxxxxxxx>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> CC: stable@xxxxxxxxxxxxxxx # v3.10+
928bea964827 appeared in v3.12. Did you mean v3.12+ instead of v3.10+?
I'd really like to get Rafael and Pavel to take a look at this.
> ---
> drivers/pci/pci-driver.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> Index: linux-2.6/drivers/pci/pci-driver.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci-driver.c
> +++ linux-2.6/drivers/pci/pci-driver.c
> @@ -519,8 +519,17 @@ static void pci_pm_set_unknown_state(str
> */
> static int pci_pm_reenable_device(struct pci_dev *pci_dev)
> {
> + u16 cmd;
> int retval;
>
> + /* update enable_cnt according to cmd register */
> + pci_read_config_word(pci_dev, PCI_COMMAND, &cmd);
> + if (!pci_dev->is_busmaster && (cmd & PCI_COMMAND_MASTER))
> + pci_dev->is_busmaster = true;
> + if (!pci_is_enabled(pci_dev) &&
> + (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)))
> + atomic_inc(&pci_dev->enable_cnt);
This doesn't feel right because we're handling enable_cnt differently here
than we do on initial boot.
On initial boot, I don't think we set enable_cnt based on whether firmware
left the IO or MEMORY bits set in the command register. Why should we
modify enable_cnt based on the command register during resume?
I could certainly believe we should do something during initial boot, too.
It just seems like we should look at the command register in both places or
neither place.
I have the same question about is_busmaster above.
> +
> /* if the device was enabled before suspend, reenable */
> retval = pci_reenable_device(pci_dev);
> /*
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