USB: work around for EHCI with quirky periodic schedules

a quirky chipset needs periodic schedules to run for a minimum
time before they can be disabled again. This enforces the requirement
with a time stamp and a calculated delay

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 20 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 9835e0713943..f5f5601701c9 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -28,6 +28,7 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/timer.h>
+#include <linux/ktime.h>
 #include <linux/list.h>
 #include <linux/interrupt.h>
 #include <linux/usb.h>
@@ -676,6 +677,7 @@ static int ehci_run (struct usb_hcd *hcd)
         ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */
         msleep(5);
         up_write(&ehci_cf_port_reset_rwsem);
+        ehci->last_periodic_enable = ktime_get_real();
 
         temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase));
         ehci_info (ehci,
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 378861b9d79a..ead5f4f2aa5a 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -111,6 +111,10 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
         switch (pdev->vendor) {
         case PCI_VENDOR_ID_INTEL:
                 ehci->need_io_watchdog = 0;
+                if (pdev->device == 0x27cc) {
+                        ehci->broken_periodic = 1;
+                        ehci_info(ehci, "using broken periodic workaround\n");
+                }
                 break;
         case PCI_VENDOR_ID_TDI:
                 if (pdev->device == PCI_DEVICE_ID_TDI_EHCI) {
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index b25cdea93a1f..a5535b5e3fe2 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -475,6 +475,8 @@ static int enable_periodic (struct ehci_hcd *ehci)
         /* make sure ehci_work scans these */
         ehci->next_uframe = ehci_readl(ehci, &ehci->regs->frame_index)
                 % (ehci->periodic_size << 3);
+        if (unlikely(ehci->broken_periodic))
+                ehci->last_periodic_enable = ktime_get_real();
         return 0;
 }
 
@@ -486,6 +488,16 @@ static int disable_periodic (struct ehci_hcd *ehci)
         if (--ehci->periodic_sched)
                 return 0;
 
+        if (unlikely(ehci->broken_periodic)) {
+                /* delay experimentally determined */
+                ktime_t safe = ktime_add_us(ehci->last_periodic_enable, 1000);
+                ktime_t now = ktime_get_real();
+                s64 delay = ktime_us_delta(safe, now);
+
+                if (unlikely(delay > 0))
+                        udelay(delay);
+        }
+
         /* did setting PSE not take effect yet?
          * takes effect only at frame boundaries...
          */
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 064e76821ff5..2d85e21ff282 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -118,6 +118,7 @@ struct ehci_hcd {			/* one per controller */
         unsigned                stamp;
         unsigned                random_frame;
         unsigned long           next_statechange;
+        ktime_t                 last_periodic_enable;
         u32                     command;
 
         /* SILICON QUIRKS */
@@ -127,6 +128,7 @@ struct ehci_hcd {			/* one per controller */
         unsigned                big_endian_desc:1;
         unsigned                has_amcc_usb23:1;
         unsigned                need_io_watchdog:1;
+        unsigned                broken_periodic:1;
 
         /* required for usb32 quirk */
         #define OHCI_CTRL_HCFS          (3 << 6)