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USB: EHCI cpufreq fix

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EHCI controllers that don't cache enough microframes can get MMF errors
when CPU frequency changes occur between the start and completion of
split interrupt transactions, due to delays in reading main memory
(caused by CPU cache snoop delays).

This patch adds a cpufreq notifier to the EHCI driver that will
inactivate split interrupt transactions during frequency transitions.
It was tested on Intel ICH7 and Serverworks/Broadcom HT1000 EHCI
controllers.

Signed-off-by: Stuart Hayes <stuart_hayes@dell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Stuart_Hayes@Dell.com
2007-05-03 08:58:49 -07:00
committed by Greg Kroah-Hartman
parent ec22559e0b
commit 196705c9bb
5 changed files with 214 additions and 0 deletions
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11
drivers/usb/host/ehci.h
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@@ -55,6 +55,12 @@ struct ehci_hcd { /* one per controller */
__u32 hcs_params; /* cached register copy */
spinlock_t lock;
#ifdef CONFIG_CPU_FREQ
struct notifier_block cpufreq_transition;
int cpufreq_changing;
struct list_head split_intr_qhs;
#endif
/* async schedule support */
struct ehci_qh *async;
struct ehci_qh *reclaim;
@@ -395,6 +401,7 @@ struct ehci_qh {
__le32 hw_next; /* see EHCI 3.6.1 */
__le32 hw_info1; /* see EHCI 3.6.2 */
#define QH_HEAD 0x00008000
#define QH_INACTIVATE 0x00000080
__le32 hw_info2; /* see EHCI 3.6.2 */
#define QH_SMASK 0x000000ff
#define QH_CMASK 0x0000ff00
@@ -437,6 +444,10 @@ struct ehci_qh {
unsigned short start; /* where polling starts */
#define NO_FRAME ((unsigned short)~0) /* pick new start */
struct usb_device *dev; /* access to TT */
#ifdef CONFIG_CPU_FREQ
struct list_head split_intr_qhs; /* list of split qhs */
__le32 was_active; /* active bit before "i" set */
#endif
} __attribute__ ((aligned (32)));
/*-------------------------------------------------------------------------*/