lkml.org 
[lkml]   [2005]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [RFC][PATCH 6/6] PCI PM: pci_save/restore_state improvements
    From
    Date
    On Wed, 2005-11-16 at 10:06 -0800, Greg KH wrote:
    > On Wed, Nov 16, 2005 at 02:26:04AM -0500, Adam Belay wrote:
    > > On Tue, 2005-11-15 at 22:31 -0800, Greg KH wrote:
    > > > On Tue, Nov 15, 2005 at 10:31:42PM -0500, Adam Belay wrote:
    > > > > This patch makes some improvements to pci_save_state and
    > > > > pci_restore_state. Instead of saving and restoring all standard
    > > > > registers (even read-only ones), it only restores necessary registers.
    > > > > Also, the command register is handled more carefully. Let me know if
    > > > > I'm missing anything important.
    > > > >
    > > > >
    > > > > --- a/drivers/pci/pm.c 2005-11-13 20:32:24.000000000 -0500
    > > > > +++ b/drivers/pci/pm.c 2005-11-13 20:29:32.000000000 -0500
    > > > > @@ -53,10 +53,13 @@
    > > > > */
    > > > > int pci_save_state(struct pci_dev *dev)
    > > > > {
    > > > > - int i;
    > > > > - /* XXX: 100% dword access ok here? */
    > > > > - for (i = 0; i < 16; i++)
    > > > > - pci_read_config_dword(dev, i * 4,&dev->saved_config_space[i]);
    > > > > + struct pci_dev_config * conf = &dev->saved_config;
    > > > > +
    > > > > + pci_read_config_word(dev, PCI_COMMAND, &conf->command);
    > > > > + pci_read_config_byte(dev, PCI_CACHE_LINE_SIZE, &conf->cacheline_size);
    > > > > + pci_read_config_byte(dev, PCI_LATENCY_TIMER, &conf->latency_timer);
    > > > > + pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &conf->interrupt_line);
    > > >
    > > > Why are we saving and restoring smaller ammounts of config space now?
    > >
    > > After looking at the spec, it seems that most of the registers we were
    > > restoring were read-only and couldn't possibly need to be restored.
    > > Also, the PCI PM spec suggests that only a subset of the registers
    > > should be restored. Finally, things like BIST should probably never be
    > > touched.
    >
    > Ok, but be aware that this _might_ cause problems for some cards/drivers
    > that were relying on the old way... As long as you don't mind me
    > assigning those bugs to you, I don't have a problem with this :)

    I'm probably going to regret this, but I'd be happy to take on any PCI
    PM subsystem bug reports. Unless I forgot a register we need to
    restore, I'm not expecting this to cause too many problems. A little
    time in -mm should shake out any issues out rather quickly.

    Thanks,
    Adam


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-11-18 00:43    [W:0.025 / U:59.412 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site