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>

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 9835e07..f5f5601 100644 (file)
--- 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 378861b..ead5f4f 100644 (file)
--- 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 b25cdea..a5535b5 100644 (file)
--- 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 064e768..2d85e21 100644 (file)
--- 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)