USB host: Move AMD PLL quirk to pci-quirks.c

This patch moves the AMD PLL quirk code in OHCI/EHCI driver to pci-quirks.c,
and exports the functions to be used by xHCI driver later.

AMD PLL quirk disable the optional PM feature inside specific
SB700/SB800/Hudson-2/3 platforms under the following conditions:

1. If an isochronous device is connected to OHCI/EHCI/xHCI port and is active;
2. Optional PM feature that powers down the internal Bus PLL when the link is
   in low power state is enabled.

Without AMD PLL quirk, USB isochronous stream may stutter or have breaks
occasionally, which greatly impair the performance of audio/video streams.

Currently AMD PLL quirk is implemented in OHCI and EHCI driver, and will be
added to xHCI driver too. They are doing similar things actually, so move
the quirk code to pci-quirks.c, which has several advantages:

1. Remove duplicate defines and functions in OHCI/EHCI (and xHCI) driver and
   make them cleaner;
2. AMD chipset information will be probed only once and then stored.
   Currently they're probed during every OHCI/EHCI initialization, move
   the detect code to pci-quirks.c saves the repeat detect cost;
3. Build up synchronization among OHCI/EHCI/xHCI driver. In current
   code, every host controller enable/disable PLL only according to
   its own status, and may enable PLL while there is still isoc transfer on
   other HCs. Move the quirk to pci-quirks.c prevents this issue.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alex He <alex.he@amd.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/usb/host/pci-quirks.h b/drivers/usb/host/pci-quirks.h
index 1564edfff6fe..4d2118cf1ff8 100644
--- a/drivers/usb/host/pci-quirks.h
+++ b/drivers/usb/host/pci-quirks.h
@@ -1,7 +1,26 @@
 #ifndef __LINUX_USB_PCI_QUIRKS_H
 #define __LINUX_USB_PCI_QUIRKS_H
 
+#ifdef CONFIG_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_amd_find_chipset_info(void);
+void usb_amd_dev_put(void);
+void usb_amd_quirk_pll_disable(void);
+void usb_amd_quirk_pll_enable(void);
+#else
+static inline void usb_amd_quirk_pll_disable(void)
+{
+	return;
+}
+static inline void usb_amd_quirk_pll_enable(void)
+{
+	return;
+}
+static inline void usb_amd_dev_put(void)
+{
+	return;
+}
+#endif  /* CONFIG_PCI */
 
 #endif  /*  __LINUX_USB_PCI_QUIRKS_H  */