[PATCH] USB: UHCI: Spruce up some comments
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(-)
diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index b04d99d..e576db5 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -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
*/
@@ -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
@@ -116,13 +112,13 @@
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;
@@ -131,6 +127,11 @@
return element;
}
+
+/*
+ * Transfer Descriptors
+ */
+
/*
* for TD <status>:
*/
@@ -183,17 +184,10 @@
*
* 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 */
@@ -205,16 +199,16 @@
/* 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;
@@ -225,6 +219,10 @@
/*
+ * 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
* of URB's. To make it easy to insert entries into the schedule, we have
@@ -254,15 +252,15 @@
*
* 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
@@ -312,8 +310,13 @@
return 0; /* int128 for 128-255 ms (Max.) */
}
+
/*
- * States for the root hub.
+ * The UHCI controller and 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
@@ -324,7 +327,7 @@
*/
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,
@@ -336,13 +339,13 @@
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 {
@@ -361,7 +364,7 @@
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 */
@@ -387,22 +390,22 @@
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 */
@@ -421,13 +424,17 @@
#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 */
@@ -438,9 +445,10 @@
unsigned long fsbrtime; /* In jiffies */
- struct list_head queue_list; /* P: uhci->frame_list_lock */
+ struct list_head queue_list;
};
+
/*
* Locking in uhci.c
*
@@ -460,6 +468,5 @@
#define PCI_VENDOR_ID_GENESYS 0x17a0
#define PCI_DEVICE_ID_GL880S_UHCI 0x8083
-#define PCI_DEVICE_ID_GL880S_EHCI 0x8084
#endif
