Re: [RFC PATCH v2] PCI/portdrv: Only disable Bus Master on kexec reboot and connected PCI devices

[Tiezhu Yang]

On 09/14/2020 12:06 PM, Lukas Wunner wrote:
> On Mon, Sep 14, 2020 at 04:29:10AM +0800, Tiezhu Yang wrote:
> > --- a/drivers/pci/pcie/portdrv_pci.c
> > +++ b/drivers/pci/pcie/portdrv_pci.c
> > @@ -143,6 +144,28 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
> >   	}
> >   
> >   	pcie_port_device_remove(dev);
> > +	pci_disable_device(dev);
> > +}
> > +
> > +static void pcie_portdrv_shutdown(struct pci_dev *dev)
> > +{
> > +	if (pci_bridge_d3_possible(dev)) {
> > +		pm_runtime_forbid(&dev->dev);
> > +		pm_runtime_get_noresume(&dev->dev);
> > +		pm_runtime_dont_use_autosuspend(&dev->dev);
> > +	}
> > +
> > +	pcie_port_device_remove(dev);
> > +
> > +	/*
> > +	 * If this is a kexec reboot, turn off Bus Master bit on the
> > +	 * device to tell it to not continue to do DMA. Don't touch
> > +	 * devices in D3cold or unknown states.
> > +	 * If it is not a kexec reboot, firmware will hit the PCI
> > +	 * devices with big hammer and stop their DMA any way.
> > +	 */
> > +	if (kexec_in_progress && (dev->current_state <= PCI_D3hot))
> > +		pci_disable_device(dev);
> The last portion of this function is already executed afterwards by
> pci_device_shutdown().  You don't need to duplicate it here:
>
> device_shutdown()
>    dev->bus->shutdown() == pci_device_shutdown()
>      drv->shutdown() == pcie_portdrv_shutdown()
>        pci_disable_device()
>      pci_disable_device()

pcie_port_device_remove() deletes pci_disable_device(dev)  at the beginning of this patch.


diff 
<https://lore.kernel.org/linux-pci/CAAhV-H5-X9OcBe3iRxF8PnKW-0j_10FVqm8cbiqW2-Lv4mTTdQ@xxxxxxxxxxxxxx/T/#iZ2e.:..:1600028950-10644-1-git-send-email-yangtiezhu::40loongson.cn:0drivers:pci:pcie:portdrv_core.c> 
--git a/drivers/pci/pcie/portdrv_core.c 
b/drivers/pci/pcie/portdrv_core.c index 50a9522..1991aca 100644 --- 
a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c 
@@ -491,7 +491,6 @@ void pcie_port_device_remove(struct pci_dev *dev)   {
 	device_for_each_child(&dev->dev, NULL, remove_iter);
 	pci_free_irq_vectors(dev);
- pci_disable_device(dev);   }

> Thanks,
>
> Lukas