[PATCH] UHCI: use one QH per endpoint, not per URB

This patch (as623) changes the uhci-hcd driver to make it use one QH per
device endpoint, instead of a QH per URB as it does now.  Numerous areas
of the code are affected by this.  For example, the distinction between
"queued" URBs and non-"queued" URBs no longer exists; all URBs belong to
a queue and some just happen to be at the queue's head.

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

1 files changed, 96 insertions, 81 deletions

diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index 8b4b887a7d41..7a9481c09a05 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -28,8 +28,9 @@
 #define   USBSTS_USBINT         0x0001  /* Interrupt due to IOC */
 #define   USBSTS_ERROR          0x0002  /* Interrupt due to error */
 #define   USBSTS_RD             0x0004  /* Resume Detect */
-#define   USBSTS_HSE            0x0008  /* Host System Error - basically PCI problems */
-#define   USBSTS_HCPE           0x0010  /* Host Controller Process Error - the scripts were buggy */
+#define   USBSTS_HSE            0x0008  /* Host System Error: PCI problems */
+#define   USBSTS_HCPE           0x0010  /* Host Controller Process Error:
+                                         * the schedule is buggy */
 #define   USBSTS_HCH            0x0020  /* HC Halted */
 
 /* Interrupt enable register */
@@ -47,7 +48,8 @@
 /* USB port status and control registers */
 #define USBPORTSC1      16
 #define USBPORTSC2      18
-#define   USBPORTSC_CCS         0x0001  /* Current Connect Status ("device present") */
+#define   USBPORTSC_CCS         0x0001  /* Current Connect Status
+                                         * ("device present") */
 #define   USBPORTSC_CSC         0x0002  /* Connect Status Change */
 #define   USBPORTSC_PE          0x0004  /* Port Enable */
 #define   USBPORTSC_PEC         0x0008  /* Port Enable Change */
@@ -71,15 +73,16 @@
 #define   USBLEGSUP_RWC         0x8f00  /* the R/WC bits */
 #define   USBLEGSUP_RO          0x5040  /* R/O and reserved bits */
 
-#define UHCI_PTR_BITS           cpu_to_le32(0x000F)
-#define UHCI_PTR_TERM           cpu_to_le32(0x0001)
-#define UHCI_PTR_QH             cpu_to_le32(0x0002)
-#define UHCI_PTR_DEPTH          cpu_to_le32(0x0004)
-#define UHCI_PTR_BREADTH        cpu_to_le32(0x0000)
+#define UHCI_PTR_BITS           __constant_cpu_to_le32(0x000F)
+#define UHCI_PTR_TERM           __constant_cpu_to_le32(0x0001)
+#define UHCI_PTR_QH             __constant_cpu_to_le32(0x0002)
+#define UHCI_PTR_DEPTH          __constant_cpu_to_le32(0x0004)
+#define UHCI_PTR_BREADTH        __constant_cpu_to_le32(0x0000)
 
 #define UHCI_NUMFRAMES          1024    /* in the frame list [array] */
 #define UHCI_MAX_SOF_NUMBER     2047    /* in an SOF packet */
-#define CAN_SCHEDULE_FRAMES     1000    /* how far future frames can be scheduled */
+#define CAN_SCHEDULE_FRAMES     1000    /* how far in the future frames
+                                         * can be scheduled */
 
 
 /*
@@ -87,38 +90,54 @@
  */
 
 /*
- * One role of a QH is to hold a queue of TDs for some endpoint.  Each QH is
- * used with one URB, and qh->element (updated by the HC) is either:
- *   - the next unprocessed TD for the URB, or
- *   - UHCI_PTR_TERM (when there's no more traffic for this endpoint), or
- *   - the QH for the next URB queued to the same endpoint.
+ * One role of a QH is to hold a queue of TDs for some endpoint.  One QH goes
+ * with each endpoint, and qh->element (updated by the HC) is either:
+ *   - the next unprocessed TD in the endpoint's queue, or
+ *   - UHCI_PTR_TERM (when there's no more traffic for this endpoint).
  *
  * The other role of a QH is to serve as a "skeleton" framelist entry, so we
  * can easily splice a QH for some endpoint into the schedule at the right
  * place.  Then qh->element is UHCI_PTR_TERM.
  *
- * In the frame list, qh->link maintains a list of QHs seen by the HC:
+ * In the schedule, qh->link maintains a list of QHs seen by the HC:
  *     skel1 --> ep1-qh --> ep2-qh --> ... --> skel2 --> ...
+ *
+ * qh->node is the software equivalent of qh->link.  The differences
+ * are that the software list is doubly-linked and QHs in the UNLINKING
+ * state are on the software list but not the hardware schedule.
+ *
+ * For bookkeeping purposes we maintain QHs even for Isochronous endpoints,
+ * but they never get added to the hardware schedule.
  */
+#define QH_STATE_IDLE           1       /* QH is not being used */
+#define QH_STATE_UNLINKING      2       /* QH has been removed from the
+                                         * schedule but the hardware may
+                                         * still be using it */
+#define QH_STATE_ACTIVE         3       /* QH is on the schedule */
+
 struct uhci_qh {
         /* Hardware fields */
-        __le32 link;                    /* Next queue */
-        __le32 element;                 /* Queue element pointer */
+        __le32 link;                    /* Next QH in the schedule */
+        __le32 element;                 /* Queue element (TD) pointer */
 
         /* Software fields */
         dma_addr_t dma_handle;
 
-        struct urb_priv *urbp;
+        struct list_head node;          /* Node in the list of QHs */
+        struct usb_host_endpoint *hep;  /* Endpoint information */
+        struct usb_device *udev;
+        struct list_head queue;         /* Queue of urbps for this QH */
+        struct uhci_qh *skel;           /* Skeleton for this QH */
 
-        struct list_head list;
-        struct list_head remove_list;
+        unsigned int unlink_frame;      /* When the QH was unlinked */
+        int state;                      /* QH_STATE_xxx; see above */
 } __attribute__((aligned(16)));
 
 /*
  * We need a special accessor for the element pointer because it is
  * subject to asynchronous updates by the controller.
  */
-static __le32 inline qh_element(struct uhci_qh *qh) {
+static inline __le32 qh_element(struct uhci_qh *qh) {
         __le32 element = qh->element;
 
         barrier();
@@ -149,11 +168,13 @@ static __le32 inline qh_element(struct uhci_qh *qh) {
 #define TD_CTRL_ACTLEN_MASK     0x7FF   /* actual length, encoded as n - 1 */
 
 #define TD_CTRL_ANY_ERROR       (TD_CTRL_STALLED | TD_CTRL_DBUFERR | \
-                                 TD_CTRL_BABBLE | TD_CTRL_CRCTIME | TD_CTRL_BITSTUFF)
+                                 TD_CTRL_BABBLE | TD_CTRL_CRCTIME | \
+                                 TD_CTRL_BITSTUFF)
 
 #define uhci_maxerr(err)                ((err) << TD_CTRL_C_ERR_SHIFT)
 #define uhci_status_bits(ctrl_sts)      ((ctrl_sts) & 0xF60000)
-#define uhci_actual_length(ctrl_sts)    (((ctrl_sts) + 1) & TD_CTRL_ACTLEN_MASK) /* 1-based */
+#define uhci_actual_length(ctrl_sts)    (((ctrl_sts) + 1) & \
+                        TD_CTRL_ACTLEN_MASK)    /* 1-based */
 
 /*
  * for TD <info>: (a.k.a. Token)
@@ -163,7 +184,7 @@ static __le32 inline qh_element(struct uhci_qh *qh) {
 #define TD_TOKEN_TOGGLE_SHIFT   19
 #define TD_TOKEN_TOGGLE         (1 << 19)
 #define TD_TOKEN_EXPLEN_SHIFT   21
-#define TD_TOKEN_EXPLEN_MASK    0x7FF           /* expected length, encoded as n - 1 */
+#define TD_TOKEN_EXPLEN_MASK    0x7FF   /* expected length, encoded as n-1 */
 #define TD_TOKEN_PID_MASK       0xFF
 
 #define uhci_explen(len)        ((((len) - 1) & TD_TOKEN_EXPLEN_MASK) << \
@@ -187,7 +208,7 @@ static __le32 inline qh_element(struct uhci_qh *qh) {
  * 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.
  */
 struct uhci_td {
         /* Hardware fields */
@@ -210,7 +231,7 @@ struct uhci_td {
  * We need a special accessor for the control/status word because it is
  * subject to asynchronous updates by the controller.
  */
-static u32 inline td_status(struct uhci_td *td) {
+static inline u32 td_status(struct uhci_td *td) {
         __le32 status = td->status;
 
         barrier();
@@ -223,17 +244,14 @@ static u32 inline td_status(struct uhci_td *td) {
  */
 
 /*
- * The UHCI driver places Interrupt, Control and Bulk into QHs both
- * to group together TDs for one transfer, and also to facilitate queuing
- * of URBs. To make it easy to insert entries into the schedule, we have
- * a skeleton of QHs for each predefined Interrupt latency, low-speed
- * control, full-speed control and terminating QH (see explanation for
- * the terminating QH below).
+ * The UHCI driver uses QHs with Interrupt, Control and Bulk URBs for
+ * automatic queuing. To make it easy to insert entries into the schedule,
+ * we have a skeleton of QHs for each predefined Interrupt latency,
+ * low-speed control, full-speed control, bulk, and terminating QH
+ * (see explanation for the terminating QH below).
  *
  * When we want to add a new QH, we add it to the end of the list for the
- * skeleton QH.
- *
- * For instance, the queue can look like this:
+ * skeleton QH.  For instance, the schedule list can look like this:
  *
  * skel int128 QH
  * dev 1 interrupt QH
@@ -256,26 +274,31 @@ static u32 inline td_status(struct uhci_td *td) {
  * - To loop back to the full-speed control queue for full-speed bandwidth
  *   reclamation.
  *
- * Isochronous transfers are stored before the start of the skeleton
- * schedule and don't use QHs. While the UHCI spec doesn't forbid the
- * use of QHs 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.
+ * There's a special skeleton QH for Isochronous QHs.  It never appears
+ * on the schedule, and Isochronous TDs go on the schedule before the
+ * the skeleton QHs.  The hardware accesses them directly rather than
+ * through their QH, which is used only for bookkeeping purposes.
+ * While the UHCI spec doesn't forbid the use of QHs 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
-#define skel_int128_qh          skelqh[0]
-#define skel_int64_qh           skelqh[1]
-#define skel_int32_qh           skelqh[2]
-#define skel_int16_qh           skelqh[3]
-#define skel_int8_qh            skelqh[4]
-#define skel_int4_qh            skelqh[5]
-#define skel_int2_qh            skelqh[6]
-#define skel_int1_qh            skelqh[7]
-#define skel_ls_control_qh      skelqh[8]
-#define skel_fs_control_qh      skelqh[9]
-#define skel_bulk_qh            skelqh[10]
-#define skel_term_qh            skelqh[11]
+#define UHCI_NUM_SKELQH         14
+#define skel_unlink_qh          skelqh[0]
+#define skel_iso_qh             skelqh[1]
+#define skel_int128_qh          skelqh[2]
+#define skel_int64_qh           skelqh[3]
+#define skel_int32_qh           skelqh[4]
+#define skel_int16_qh           skelqh[5]
+#define skel_int8_qh            skelqh[6]
+#define skel_int4_qh            skelqh[7]
+#define skel_int2_qh            skelqh[8]
+#define skel_int1_qh            skelqh[9]
+#define skel_ls_control_qh      skelqh[10]
+#define skel_fs_control_qh      skelqh[11]
+#define skel_bulk_qh            skelqh[12]
+#define skel_term_qh            skelqh[13]
 
 /*
  * Search tree for determining where <interval> fits in the skelqh[]
@@ -293,21 +316,21 @@ static inline int __interval_to_skel(int interval)
         if (interval < 16) {
                 if (interval < 4) {
                         if (interval < 2)
-                                return 7;       /* int1 for 0-1 ms */
-                        return 6;               /* int2 for 2-3 ms */
+                                return 9;       /* int1 for 0-1 ms */
+                        return 8;               /* int2 for 2-3 ms */
                 }
                 if (interval < 8)
-                        return 5;               /* int4 for 4-7 ms */
-                return 4;                       /* int8 for 8-15 ms */
+                        return 7;               /* int4 for 4-7 ms */
+                return 6;                       /* int8 for 8-15 ms */
         }
         if (interval < 64) {
                 if (interval < 32)
-                        return 3;               /* int16 for 16-31 ms */
-                return 2;                       /* int32 for 32-63 ms */
+                        return 5;               /* int16 for 16-31 ms */
+                return 4;                       /* int32 for 32-63 ms */
         }
         if (interval < 128)
-                return 1;                       /* int64 for 64-127 ms */
-        return 0;                               /* int128 for 128-255 ms (Max.) */
+                return 3;                       /* int64 for 64-127 ms */
+        return 2;                               /* int128 for 128-255 ms (Max.) */
 }
 
 
@@ -363,12 +386,12 @@ struct uhci_hcd {
 
         spinlock_t lock;
 
-        dma_addr_t frame_dma_handle;            /* Hardware frame list */
+        dma_addr_t frame_dma_handle;    /* Hardware frame list */
         __le32 *frame;
-        void **frame_cpu;                       /* CPU's frame list */
+        void **frame_cpu;               /* CPU's frame list */
 
-        int fsbr;                               /* Full-speed bandwidth reclamation */
-        unsigned long fsbrtimeout;              /* FSBR delay */
+        int fsbr;                       /* Full-speed bandwidth reclamation */
+        unsigned long fsbrtimeout;      /* FSBR delay */
 
         enum uhci_rh_state rh_state;
         unsigned long auto_stop_time;           /* When to AUTO_STOP */
@@ -392,24 +415,19 @@ struct uhci_hcd {
         /* Main list of URBs currently controlled by this HC */
         struct list_head urb_list;
 
-        /* List of QHs that are done, but waiting to be unlinked (race) */
-        struct list_head qh_remove_list;
-        unsigned int qh_remove_age;             /* Age in frames */
-
         /* List of TDs that are done, but waiting to be freed (race) */
         struct list_head td_remove_list;
         unsigned int td_remove_age;             /* Age in frames */
 
-        /* List of asynchronously unlinked URBs */
-        struct list_head urb_remove_list;
-        unsigned int urb_remove_age;            /* Age in frames */
-
         /* List of URBs awaiting completion callback */
         struct list_head complete_list;
 
+        struct list_head idle_qh_list;          /* Where the idle QHs live */
+
         int rh_numports;                        /* Number of root-hub ports */
 
         wait_queue_head_t waitqh;               /* endpoint_disable waiters */
+        int num_waiting;                        /* Number of waiters */
 };
 
 /* Convert between a usb_hcd pointer and the corresponding uhci_hcd */
@@ -430,22 +448,19 @@ static inline struct usb_hcd *uhci_to_hcd(struct uhci_hcd *uhci)
  */
 struct urb_priv {
         struct list_head urb_list;
+        struct list_head node;          /* Node in the QH's urbp list */
 
         struct urb *urb;
 
         struct uhci_qh *qh;             /* QH for this URB */
         struct list_head td_list;
 
-        unsigned fsbr : 1;              /* URB turned on FSBR */
-        unsigned fsbr_timeout : 1;      /* URB timed out on FSBR */
-        unsigned queued : 1;            /* QH was queued (not linked in) */
-        unsigned short_control_packet : 1;      /* If we get a short packet during */
-                                                /*  a control transfer, retrigger */
-                                                /*  the status phase */
-
         unsigned long fsbrtime;         /* In jiffies */
 
-        struct list_head queue_list;
+        unsigned fsbr : 1;              /* URB turned on FSBR */
+        unsigned fsbr_timeout : 1;      /* URB timed out on FSBR */
+        unsigned short_transfer : 1;    /* URB got a short transfer, no
+                                         * need to rescan */
 };