Re: [RFC 31/32] usb: handle HAS_IOPORT dependencies

Alan Stern
2021-12-27T20:36:29Z

On Mon, Dec 27, 2021 at 05:43:16PM +0100, Niklas Schnelle wrote:
> In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> not being declared. We thus need to guard sections of code calling them
> as alternative access methods with CONFIG_HAS_IOPORT checks. Similarly
> drivers requiring these functions need to depend on HAS_IOPORT.

A few things in here can be improved.

>
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
> drivers/usb/core/hcd-pci.c | 3 +-
> drivers/usb/host/Kconfig | 4 +-
> drivers/usb/host/pci-quirks.c | 127 ++++++++++++++++++----------------
> drivers/usb/host/pci-quirks.h | 33 ++++++---
> drivers/usb/host/uhci-hcd.c | 2 +-
> drivers/usb/host/uhci-hcd.h | 77 ++++++++++++++-------
> 6 files changed, 148 insertions(+), 98 deletions(-)

> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index ef08d68b9714..bba320194027 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c

> +#ifdef CONFIG_USB_PCI_AMD
> +#if IS_ENABLED(CONFIG_USB_UHCI_HCD) && defined(CONFIG_HAS_IOPORT)

In the original, the following code will be compiled even if
CONFIG_USB_UHCI_HCD is not enabled. You shouldn't change that.

> /*
> * Make sure the controller is completely inactive, unable to
> * generate interrupts or do DMA.

> @@ -1273,7 +1277,8 @@ static void quirk_usb_early_handoff(struct pci_dev *pdev)
> "Can't enable PCI device, BIOS handoff failed.\n");
> return;
> }
> - if (pdev->class == PCI_CLASS_SERIAL_USB_UHCI)
> + if (IS_ENABLED(CONFIG_USB_UHCI_HCD) &&
> + pdev->class == PCI_CLASS_SERIAL_USB_UHCI)
> quirk_usb_handoff_uhci(pdev);

Same idea here.

> else if (pdev->class == PCI_CLASS_SERIAL_USB_OHCI)
> quirk_usb_handoff_ohci(pdev);
> diff --git a/drivers/usb/host/pci-quirks.h b/drivers/usb/host/pci-quirks.h
> index e729de21fad7..42eb18be37af 100644
> --- a/drivers/usb/host/pci-quirks.h
> +++ b/drivers/usb/host/pci-quirks.h
> @@ -2,33 +2,50 @@
> #ifndef __LINUX_USB_PCI_QUIRKS_H
> #define __LINUX_USB_PCI_QUIRKS_H
>
> -#ifdef CONFIG_USB_PCI
> void uhci_reset_hc(struct pci_dev *pdev, unsigned long base);
> int uhci_check_and_reset_hc(struct pci_dev *pdev, unsigned long base);
> -int usb_hcd_amd_remote_wakeup_quirk(struct pci_dev *pdev);
> +
> +struct pci_dev;

This can't be right; struct pci_dev is referred to three lines earlier.
You could move this up, but it may not be needed at all.

> diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
> index 8ae5ccd26753..8e30116b6fd2 100644
> --- a/drivers/usb/host/uhci-hcd.h
> +++ b/drivers/usb/host/uhci-hcd.h
> @@ -586,12 +586,14 @@ static inline int uhci_aspeed_reg(unsigned int reg)
>
> static inline u32 uhci_readl(const struct uhci_hcd *uhci, int reg)
> {
> +#ifdef CONFIG_HAS_IOPORT
> if (uhci_has_pci_registers(uhci))
> return inl(uhci->io_addr + reg);
> - else if (uhci_is_aspeed(uhci))
> +#endif

Instead of making all these changes (here and in the hunks below), you
can simply modify the definition of uhci_has_pci_registers() so that it
always gives 0 when CONFIG_HAS_IOPORT is N.

Alan Stern