On Sat, Dec 13, 2008 at 07:37:30PM +0000, Ben Hutchings wrote:
> During an online device reset it may be useful to disable bus-mastering.
> pci_disable_device() does that, and far more besides, so is not suitable
> for an online reset.
>
> Add pci_clear_master() which does just this.
>
> Signed-off-by: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Reviewed-by: Grant Grundler <grundler@xxxxxxxxxxxxxxxx>
> ---
> drivers/pci/pci.c | 39 ++++++++++++++++++++++++++++-----------
> include/linux/pci.h | 1 +
Since this exports a new symbol, can you update Documentation/PCI/pci.txt
to include pci_clear_master() where appropriate?
I'm ok if it's a separate patch from the two you sent.
thanks,
grant
> 2 files changed, 29 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 3222f90..fbb4cdc 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1609,6 +1609,22 @@ int pci_request_regions_exclusive(struct pci_dev *pdev, const char *res_name)
> ((1 << 6) - 1), res_name);
> }
>
> +static void __pci_set_master(struct pci_dev *dev, bool enable)
> +{
> + u16 old_cmd, cmd;
> +
> + pci_read_config_word(dev, PCI_COMMAND, &old_cmd);
> + if (enable)
> + cmd = old_cmd | PCI_COMMAND_MASTER;
> + else
> + cmd = old_cmd & ~PCI_COMMAND_MASTER;
> + if (cmd != old_cmd) {
> + dev_dbg(&dev->dev, "%s bus mastering\n",
> + enable ? "enabling" : "disabling");
> + pci_write_config_word(dev, PCI_COMMAND, cmd);
> + }
> + dev->is_busmaster = enable;
> +}
>
> /**
> * pci_set_master - enables bus-mastering for device dev
> @@ -1617,21 +1633,21 @@ int pci_request_regions_exclusive(struct pci_dev *pdev, const char *res_name)
> * Enables bus-mastering on the device and calls pcibios_set_master()
> * to do the needed arch specific settings.
> */
> -void
> -pci_set_master(struct pci_dev *dev)
> +void pci_set_master(struct pci_dev *dev)
> {
> - u16 cmd;
> -
> - pci_read_config_word(dev, PCI_COMMAND, &cmd);
> - if (! (cmd & PCI_COMMAND_MASTER)) {
> - dev_dbg(&dev->dev, "enabling bus mastering\n");
> - cmd |= PCI_COMMAND_MASTER;
> - pci_write_config_word(dev, PCI_COMMAND, cmd);
> - }
> - dev->is_busmaster = 1;
> + __pci_set_master(dev, true);
> pcibios_set_master(dev);
> }
>
> +/**
> + * pci_clear_master - disables bus-mastering for device dev
> + * @dev: the PCI device to disable
> + */
> +void pci_clear_master(struct pci_dev *dev)
> +{
> + __pci_set_master(dev, false);
Did you want to use dev->is_busmaster here to avoid the Config read?
Not sure it's useful to do that...just tossing the idea out there.
As-is is fine too.
thanks,
grant
> +}
> +
> #ifdef PCI_DISABLE_MWI
> int pci_set_mwi(struct pci_dev *dev)
> {
> @@ -2266,6 +2282,7 @@ EXPORT_SYMBOL(pci_release_selected_regions);
> EXPORT_SYMBOL(pci_request_selected_regions);
> EXPORT_SYMBOL(pci_request_selected_regions_exclusive);
> EXPORT_SYMBOL(pci_set_master);
> +EXPORT_SYMBOL(pci_clear_master);
> EXPORT_SYMBOL(pci_set_mwi);
> EXPORT_SYMBOL(pci_try_set_mwi);
> EXPORT_SYMBOL(pci_clear_mwi);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 43b863f..2fe7358 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -624,6 +624,7 @@ static inline int pci_is_managed(struct pci_dev *pdev)
>
> void pci_disable_device(struct pci_dev *dev);
> void pci_set_master(struct pci_dev *dev);
> +void pci_clear_master(struct pci_dev *dev);
> int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state);
> #define HAVE_PCI_SET_MWI
> int __must_check pci_set_mwi(struct pci_dev *dev);
> --
> 1.5.5
>
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