On Fri, 14 Oct 2011 tom.leiming@xxxxxxxxx wrote:
> From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
>
> This patch tries to apply the new driver probe deferral mechanism to
> uhci/ohci companion driver so that ehci driver can be probed before
> uhci/ohci companion driver.
>
> Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
> Cc: Manjunath GKondaiah <manjunath.gkondaiah@xxxxxxxxxx>
> Cc: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Dilan Lee <dilee@xxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
> ---
> drivers/usb/core/hcd-pci.c | 26 ++++++++++++++++++++++++++
> 1 files changed, 26 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
> index ce22f4a..f64575e 100644
> --- a/drivers/usb/core/hcd-pci.c
> +++ b/drivers/usb/core/hcd-pci.c
> @@ -183,6 +204,11 @@ int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
> if (!driver)
> return -EINVAL;
>
> + if (has_ehci_companion(dev, &ehci_comp)) {
> + if (!dev_get_drvdata(&ehci_comp->dev))
> + return -EPROBE_DEFER;
> + }
> +
This is wrong. It will prevent UHCI or OHCI controllers from being
used in situations where there is no EHCI driver available.
The deferral mechanism is meant for situations where one device can't
be used unless another device is working. But UHCI and OHCI
controllers work just fine when the companion EHCI controller is down.
Alan Stern
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