Hi,
this solves a problem mainly seen in uvcvideo cameras.
It is needed in mainline and stable as it is for broken hardware
meaning all kernel versions are affected.
Regards
Oliver
SIgned-off-by: Oliver Neukum <oliver@xxxxxxxxxx>
--
commit c222ad7196f0baa2b7341bfaf8c2821aaa089c3a
Author: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Fri Nov 27 15:08:08 2009 +0100
usb: add a work around for a quirk with the periodic schedule
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
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 9835e07..f5f5601 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 378861b..ead5f4f 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 b25cdea..5b68a34 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 064e768..2d85e21 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)
--
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