• Andiry Xu's avatar
    USB host: Move AMD PLL quirk to pci-quirks.c · ad93562b
    Andiry Xu authored
    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: default avatarAndiry Xu <andiry.xu@amd.com>
    Cc: David Brownell <dbrownell@users.sourceforge.net>
    Cc: Alex He <alex.he@amd.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    ad93562b
ohci-hcd.c 33.3 KB