usb/isp1760: Use polling instead of SOF interrupts to fix Errata 2

Errata 2 for the isp1760 explains that the chip sometimes does not issue
interrupts when an ATL (bulk or control) transfer is completed. There are
several issues with the current work-around (SOF interrupts) for this:

1) It seems the chip sometimes does not even set the done bit for a
   completed transfer, in which case SOF interrupts does not solve
   the problem since we still check the done map to find out which
   transfer descriptors to handle.

2) The above point seems to happen only when ATL and SOF interrupts
   are enabled at the same time. However, disabling ATL interrupts
   increases the latency between transfer completion and handling.
   This is very noticeable in the testusb suite, which take several
   minutes more to run with ATL interrupts disabled.

This patch removes the code to switch on SOF interrupts, and instead
use a kernel timer to periodically check for "old" descriptors that
have their VALID and ACTIVE flags unset, indicating completion, thus
avoiding the dependency on the chip's done map (and SOF interrupts)
to find transfers affected by this HW bug.

[bigeasy@linutronix: 80 lines limit]

Signed-off-by: Arvid Brodin <arvid.brodin@enea.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 1 deletions

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)