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[PATCH] USB: UHCI: Spruce up some comments
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This patch (as570) changes some comments in the uhci-hcd header file and
removes an unused declaration (something I forgot to erase in an earlier
patch).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 drivers/usb/host/uhci-hcd.h |   91 +++++++++++++++++++++++---------------------
 1 file changed, 49 insertions(+), 42 deletions(-)
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Alan Stern authored and Greg Kroah-Hartman committed Oct 28, 2005
1 parent d09d36a commit 8b262bd
Showing 1 changed file with 49 additions and 42 deletions.
91 changes: 49 additions & 42 deletions drivers/usb/host/uhci-hcd.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#define usb_packetid(pipe) (usb_pipein(pipe) ? USB_PID_IN : USB_PID_OUT)
#define PIPE_DEVEP_MASK 0x0007ff00


/*
* Universal Host Controller Interface data structures and defines
*/
Expand Down Expand Up @@ -82,15 +83,10 @@
#define UHCI_MAX_SOF_NUMBER 2047 /* in an SOF packet */
#define CAN_SCHEDULE_FRAMES 1000 /* how far future frames can be scheduled */

struct uhci_frame_list {
__le32 frame[UHCI_NUMFRAMES];

void *frame_cpu[UHCI_NUMFRAMES];

dma_addr_t dma_handle;
};

struct urb_priv;
/*
* Queue Headers
*/

/*
* One role of a QH is to hold a queue of TDs for some endpoint. Each QH is
Expand All @@ -116,13 +112,13 @@ struct uhci_qh {

struct urb_priv *urbp;

struct list_head list; /* P: uhci->frame_list_lock */
struct list_head remove_list; /* P: uhci->remove_list_lock */
struct list_head list;
struct list_head remove_list;
} __attribute__((aligned(16)));

/*
* We need a special accessor for the element pointer because it is
* subject to asynchronous updates by the controller
* subject to asynchronous updates by the controller.
*/
static __le32 inline qh_element(struct uhci_qh *qh) {
__le32 element = qh->element;
Expand All @@ -131,6 +127,11 @@ static __le32 inline qh_element(struct uhci_qh *qh) {
return element;
}


/*
* Transfer Descriptors
*/

/*
* for TD <status>:
*/
Expand Down Expand Up @@ -183,17 +184,10 @@ static __le32 inline qh_element(struct uhci_qh *qh) {
*
* That's silly, the hardware doesn't care. The hardware only cares that
* the hardware words are 16-byte aligned, and we can have any amount of
* sw space after the TD entry as far as I can tell.
*
* But let's just go with the documentation, at least for 32-bit machines.
* On 64-bit machines we probably want to take advantage of the fact that
* hw doesn't really care about the size of the sw-only area.
*
* Alas, not anymore, we have more than 4 words for software, woops.
* Everything still works tho, surprise! -jerdfelt
* sw space after the TD entry.
*
* td->link points to either another TD (not necessarily for the same urb or
* even the same endpoint), or nothing (PTR_TERM), or a QH (for queued urbs)
* even the same endpoint), or nothing (PTR_TERM), or a QH (for queued urbs).
*/
struct uhci_td {
/* Hardware fields */
Expand All @@ -205,16 +199,16 @@ struct uhci_td {
/* Software fields */
dma_addr_t dma_handle;

struct list_head list; /* P: urb->lock */
struct list_head remove_list; /* P: uhci->td_remove_list_lock */
struct list_head list;
struct list_head remove_list;

int frame; /* for iso: what frame? */
struct list_head fl_list; /* P: uhci->frame_list_lock */
struct list_head fl_list;
} __attribute__((aligned(16)));

/*
* We need a special accessor for the control/status word because it is
* subject to asynchronous updates by the controller
* subject to asynchronous updates by the controller.
*/
static u32 inline td_status(struct uhci_td *td) {
__le32 status = td->status;
Expand All @@ -224,6 +218,10 @@ static u32 inline td_status(struct uhci_td *td) {
}


/*
* Skeleton Queue Headers
*/

/*
* The UHCI driver places Interrupt, Control and Bulk into QH's both
* to group together TD's for one transfer, and also to faciliate queuing
Expand Down Expand Up @@ -254,15 +252,15 @@ static u32 inline td_status(struct uhci_td *td) {
*
* The terminating QH is used for 2 reasons:
* - To place a terminating TD which is used to workaround a PIIX bug
* (see Intel errata for explanation)
* (see Intel errata for explanation), and
* - To loop back to the full-speed control queue for full-speed bandwidth
* reclamation
* reclamation.
*
* Isochronous transfers are stored before the start of the skeleton
* schedule and don't use QH's. While the UHCI spec doesn't forbid the
* use of QH's for Isochronous, it doesn't use them either. Since we don't
* need to use them either, we follow the spec diagrams in hope that it'll
* be more compatible with future UHCI implementations.
* use of QH's for Isochronous, it doesn't use them either. And the spec
* says that queues never advance on an error completion status, which
* makes them totally unsuitable for Isochronous transfers.
*/

#define UHCI_NUM_SKELQH 12
Expand Down Expand Up @@ -312,8 +310,13 @@ static inline int __interval_to_skel(int interval)
return 0; /* int128 for 128-255 ms (Max.) */
}


/*
* The UHCI controller and root hub
*/

/*
* States for the root hub.
* States for the root hub:
*
* To prevent "bouncing" in the presence of electrical noise,
* when there are no devices attached we delay for 1 second in the
Expand All @@ -324,7 +327,7 @@ static inline int __interval_to_skel(int interval)
*/
enum uhci_rh_state {
/* In the following states the HC must be halted.
* These two must come first */
* These two must come first. */
UHCI_RH_RESET,
UHCI_RH_SUSPENDED,

Expand All @@ -336,13 +339,13 @@ enum uhci_rh_state {
UHCI_RH_SUSPENDING,

/* In the following states it's an error if the HC is halted.
* These two must come last */
* These two must come last. */
UHCI_RH_RUNNING, /* The normal state */
UHCI_RH_RUNNING_NODEVS, /* Running with no devices attached */
};

/*
* This describes the full uhci information.
* The full UHCI controller information:
*/
struct uhci_hcd {

Expand All @@ -361,7 +364,7 @@ struct uhci_hcd {
spinlock_t lock;

dma_addr_t frame_dma_handle; /* Hardware frame list */
__le32 *frame; /* P: uhci->lock */
__le32 *frame;
void **frame_cpu; /* CPU's frame list */

int fsbr; /* Full-speed bandwidth reclamation */
Expand All @@ -387,22 +390,22 @@ struct uhci_hcd {
unsigned long ports_timeout; /* Time to stop signalling */

/* Main list of URB's currently controlled by this HC */
struct list_head urb_list; /* P: uhci->lock */
struct list_head urb_list;

/* List of QH's that are done, but waiting to be unlinked (race) */
struct list_head qh_remove_list; /* P: uhci->lock */
struct list_head qh_remove_list;
unsigned int qh_remove_age; /* Age in frames */

/* List of TD's that are done, but waiting to be freed (race) */
struct list_head td_remove_list; /* P: uhci->lock */
struct list_head td_remove_list;
unsigned int td_remove_age; /* Age in frames */

/* List of asynchronously unlinked URB's */
struct list_head urb_remove_list; /* P: uhci->lock */
struct list_head urb_remove_list;
unsigned int urb_remove_age; /* Age in frames */

/* List of URB's awaiting completion callback */
struct list_head complete_list; /* P: uhci->lock */
struct list_head complete_list;

int rh_numports; /* Number of root-hub ports */

Expand All @@ -421,13 +424,17 @@ static inline struct usb_hcd *uhci_to_hcd(struct uhci_hcd *uhci)

#define uhci_dev(u) (uhci_to_hcd(u)->self.controller)


/*
* Private per-URB data
*/
struct urb_priv {
struct list_head urb_list;

struct urb *urb;

struct uhci_qh *qh; /* QH for this URB */
struct list_head td_list; /* P: urb->lock */
struct list_head td_list;

unsigned fsbr : 1; /* URB turned on FSBR */
unsigned fsbr_timeout : 1; /* URB timed out on FSBR */
Expand All @@ -438,9 +445,10 @@ struct urb_priv {

unsigned long fsbrtime; /* In jiffies */

struct list_head queue_list; /* P: uhci->frame_list_lock */
struct list_head queue_list;
};


/*
* Locking in uhci.c
*
Expand All @@ -460,6 +468,5 @@ struct urb_priv {

#define PCI_VENDOR_ID_GENESYS 0x17a0
#define PCI_DEVICE_ID_GL880S_UHCI 0x8083
#define PCI_DEVICE_ID_GL880S_EHCI 0x8084

#endif

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