2 files changed, 96 insertions, 45 deletions

diff --git a/drivers/usb/host/isp1760-hcd.c b/drivers/usb/host/isp1760-hcd.c
index e399e235f656..14c9238a5017 100644
--- a/drivers/usb/host/isp1760-hcd.c
+++ b/drivers/usb/host/isp1760-hcd.c
@@ -21,6 +21,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/mm.h>
+#include <linux/timer.h>
 #include <asm/unaligned.h>
 #include <asm/cacheflush.h>
 
@@ -39,7 +40,6 @@ struct isp1760_hcd {
         int                     int_done_map;
         struct memory_chunk memory_pool[BLOCKS];
         struct list_head        controlqhs, bulkqhs, interruptqhs;
-        int active_ptds;
 
         /* periodic schedule support */
 #define DEFAULT_I_TDPS          1024
@@ -489,10 +489,6 @@ static int isp1760_hc_setup(struct usb_hcd *hcd)
                            16 : 32, (priv->devflags & ISP1760_FLAG_ANALOG_OC) ?
                            "analog" : "digital");
 
-        /* This is weird: at the first plug-in of a device there seems to be
-           one packet queued that never gets returned? */
-        priv->active_ptds = -1;
-
         /* ATL reset */
         reg_write32(hcd->regs, HC_HW_MODE_CTRL, hwmode | ALL_ATX_RESET);
         mdelay(10);
@@ -741,8 +737,8 @@ static void start_bus_transfer(struct usb_hcd *hcd, u32 ptd_offset, int slot,
         qh->slot = slot;
         qtd->status = QTD_XFER_STARTED; /* Set this before writing ptd, since
                 interrupt routine may preempt and expects this value. */
+        slots[slot].timestamp = jiffies;
         ptd_write(hcd->regs, ptd_offset, slot, ptd);
-        priv->active_ptds++;
 
         /* Make sure done map has not triggered from some unlinked transfer */
         if (ptd_offset == ATL_PTD_OFFSET) {
@@ -1091,11 +1087,9 @@ static int check_atl_transfer(struct usb_hcd *hcd, struct ptd *ptd,
         return PTD_STATE_QTD_DONE;
 }
 
-static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
+static void handle_done_ptds(struct usb_hcd *hcd)
 {
         struct isp1760_hcd *priv = hcd_to_priv(hcd);
-        u32 imask;
-        irqreturn_t irqret = IRQ_NONE;
         struct ptd ptd;
         struct isp1760_qh *qh;
         int slot;
@@ -1104,27 +1098,14 @@ static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
         u32 ptd_offset;
         struct isp1760_qtd *qtd;
         int modified;
-        static int last_active_ptds;
-        int int_skip_map, atl_skip_map;
-
-        spin_lock(&priv->lock);
-
-        if (!(hcd->state & HC_STATE_RUNNING))
-                goto leave;
-
-        imask = reg_read32(hcd->regs, HC_INTERRUPT_REG);
-        if (unlikely(!imask))
-                goto leave;
-        reg_write32(hcd->regs, HC_INTERRUPT_REG, imask); /* Clear */
+        int skip_map;
 
-        int_skip_map = reg_read32(hcd->regs, HC_INT_PTD_SKIPMAP_REG);
-        atl_skip_map = reg_read32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG);
-        priv->int_done_map |= reg_read32(hcd->regs, HC_INT_PTD_DONEMAP_REG);
-        priv->atl_done_map |= reg_read32(hcd->regs, HC_ATL_PTD_DONEMAP_REG);
-        priv->int_done_map &= ~int_skip_map;
-        priv->atl_done_map &= ~atl_skip_map;
+        skip_map = reg_read32(hcd->regs, HC_INT_PTD_SKIPMAP_REG);
+        priv->int_done_map &= ~skip_map;
+        skip_map = reg_read32(hcd->regs, HC_ATL_PTD_SKIPMAP_REG);
+        priv->atl_done_map &= ~skip_map;
 
-        modified = priv->int_done_map | priv->atl_done_map;
+        modified = priv->int_done_map || priv->atl_done_map;
 
         while (priv->int_done_map || priv->atl_done_map) {
                 if (priv->int_done_map) {
@@ -1163,7 +1144,6 @@ static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
                 slots[slot].qtd = NULL;
                 qh = slots[slot].qh;
                 slots[slot].qh = NULL;
-                priv->active_ptds--;
                 qh->slot = -1;
 
                 WARN_ON(qtd->status != QTD_XFER_STARTED);
@@ -1234,22 +1214,28 @@ static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
 
         if (modified)
                 schedule_ptds(hcd);
+}
 
-        /* ISP1760 Errata 2 explains that interrupts may be missed (or not
-           happen?) if two USB devices are running simultaneously. Perhaps
-           this happens when a PTD is finished during interrupt handling;
-           enable SOF interrupts if PTDs are still scheduled when exiting this
-           interrupt handler, just to be safe. */
+static irqreturn_t isp1760_irq(struct usb_hcd *hcd)
+{
+        struct isp1760_hcd *priv = hcd_to_priv(hcd);
+        u32 imask;
+        irqreturn_t irqret = IRQ_NONE;
 
-        if (priv->active_ptds != last_active_ptds) {
-                if (priv->active_ptds > 0)
-                        reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
-                                                INTERRUPT_ENABLE_SOT_MASK);
-                else
-                        reg_write32(hcd->regs, HC_INTERRUPT_ENABLE,
-                                                INTERRUPT_ENABLE_MASK);
-                last_active_ptds = priv->active_ptds;
-        }
+        spin_lock(&priv->lock);
+
+        if (!(hcd->state & HC_STATE_RUNNING))
+                goto leave;
+
+        imask = reg_read32(hcd->regs, HC_INTERRUPT_REG);
+        if (unlikely(!imask))
+                goto leave;
+        reg_write32(hcd->regs, HC_INTERRUPT_REG, imask); /* Clear */
+
+        priv->int_done_map |= reg_read32(hcd->regs, HC_INT_PTD_DONEMAP_REG);
+        priv->atl_done_map |= reg_read32(hcd->regs, HC_ATL_PTD_DONEMAP_REG);
+
+        handle_done_ptds(hcd);
 
         irqret = IRQ_HANDLED;
 leave:
@@ -1258,6 +1244,63 @@ leave:
         return irqret;
 }
 
+/*
+ * Workaround for problem described in chip errata 2:
+ *
+ * Sometimes interrupts are not generated when ATL (not INT?) completion occurs.
+ * One solution suggested in the errata is to use SOF interrupts _instead_of_
+ * ATL done interrupts (the "instead of" might be important since it seems
+ * enabling ATL interrupts also causes the chip to sometimes - rarely - "forget"
+ * to set the PTD's done bit in addition to not generating an interrupt!).
+ *
+ * So if we use SOF + ATL interrupts, we sometimes get stale PTDs since their
+ * done bit is not being set. This is bad - it blocks the endpoint until reboot.
+ *
+ * If we use SOF interrupts only, we get latency between ptd completion and the
+ * actual handling. This is very noticeable in testusb runs which takes several
+ * minutes longer without ATL interrupts.
+ *
+ * A better solution is to run the code below every SLOT_CHECK_PERIOD ms. If it
+ * finds active ATL slots which are older than SLOT_TIMEOUT ms, it checks the
+ * slot's ACTIVE and VALID bits. If these are not set, the ptd is considered
+ * completed and its done map bit is set.
+ *
+ * The values of SLOT_TIMEOUT and SLOT_CHECK_PERIOD have been arbitrarily chosen
+ * not to cause too much lag when this HW bug occurs, while still hopefully
+ * ensuring that the check does not falsely trigger.
+ */
+#define SLOT_TIMEOUT 180
+#define SLOT_CHECK_PERIOD 200
+static struct timer_list errata2_timer;
+
+void errata2_function(unsigned long data)
+{
+        struct usb_hcd *hcd = (struct usb_hcd *) data;
+        struct isp1760_hcd *priv = hcd_to_priv(hcd);
+        int slot;
+        struct ptd ptd;
+        unsigned long spinflags;
+
+        spin_lock_irqsave(&priv->lock, spinflags);
+
+        for (slot = 0; slot < 32; slot++)
+                if ((priv->atl_slots[slot].qh || priv->atl_slots[slot].qtd) &&
+                                time_after(jiffies + SLOT_TIMEOUT * HZ / 1000,
+                                priv->atl_slots[slot].timestamp)) {
+                        ptd_read(hcd->regs, ATL_PTD_OFFSET, slot, &ptd);
+                        if (!FROM_DW0_VALID(ptd.dw0) &&
+                                        !FROM_DW3_ACTIVE(ptd.dw3))
+                                priv->atl_done_map |= 1 << slot;
+                }
+
+        handle_done_ptds(hcd);
+
+        spin_unlock_irqrestore(&priv->lock, spinflags);
+
+        errata2_timer.expires = jiffies + SLOT_CHECK_PERIOD * HZ / 1000;
+        add_timer(&errata2_timer);
+}
+
 static int isp1760_run(struct usb_hcd *hcd)
 {
         int retval;
@@ -1303,6 +1346,12 @@ static int isp1760_run(struct usb_hcd *hcd)
         if (retval)
                 return retval;
 
+        init_timer(&errata2_timer);
+        errata2_timer.function = errata2_function;
+        errata2_timer.data = (unsigned long) hcd;
+        errata2_timer.expires = jiffies + SLOT_CHECK_PERIOD * HZ / 1000;
+        add_timer(&errata2_timer);
+
         chipid = reg_read32(hcd->regs, HC_CHIP_ID_REG);
         dev_info(hcd->self.controller, "USB ISP %04x HW rev. %d started\n",
                                         chipid & 0xffff, chipid >> 16);
@@ -1561,7 +1610,6 @@ static void kill_transfer(struct usb_hcd *hcd, struct urb *urb,
         }
 
         qh->slot = -1;
-        priv->active_ptds--;
 }
 
 static int isp1760_urb_dequeue(struct usb_hcd *hcd, struct urb *urb,
@@ -2012,6 +2060,8 @@ static void isp1760_stop(struct usb_hcd *hcd)
         struct isp1760_hcd *priv = hcd_to_priv(hcd);
         u32 temp;
 
+        del_timer(&errata2_timer);
+
         isp1760_hub_control(hcd, ClearPortFeature, USB_PORT_FEAT_POWER, 1,
                         NULL, 0);
         mdelay(20);
diff --git a/drivers/usb/host/isp1760-hcd.h b/drivers/usb/host/isp1760-hcd.h
index 014a7dfadf91..fda0f2d54e3d 100644
--- a/drivers/usb/host/isp1760-hcd.h
+++ b/drivers/usb/host/isp1760-hcd.h
@@ -73,7 +73,6 @@ void deinit_kmem_cache(void);
 #define HC_EOT_INT              (1 << 3)
 #define HC_SOT_INT              (1 << 1)
 #define INTERRUPT_ENABLE_MASK   (HC_INTL_INT | HC_ATL_INT)
-#define INTERRUPT_ENABLE_SOT_MASK       (HC_SOT_INT)
 
 #define HC_ISO_IRQ_MASK_OR_REG  0x318
 #define HC_INT_IRQ_MASK_OR_REG  0x31C
@@ -107,6 +106,7 @@ struct ptd {
 struct slotinfo {
         struct isp1760_qh *qh;
         struct isp1760_qtd *qtd;
+        unsigned long timestamp;
 };
 
 
@@ -188,6 +188,7 @@ struct memory_chunk {
 #define DW3_BABBLE_BIT                  (1 << 29)
 #define DW3_HALT_BIT                    (1 << 30)
 #define DW3_ACTIVE_BIT                  (1 << 31)
+#define FROM_DW3_ACTIVE(x)              (((x) >> 31) & 0x01)
 
 #define INT_UNDERRUN                    (1 << 2)
 #define INT_BABBLE                      (1 << 1)