aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/usb/host/uhci-q.c
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2006-10-05 09:55:46 -0400
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 10:10:12 -0400
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /drivers/usb/host/uhci-q.c
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Diffstat (limited to 'drivers/usb/host/uhci-q.c')
-rw-r--r--drivers/usb/host/uhci-q.c15
1 files changed, 7 insertions, 8 deletions
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 431e8f31f1a9..06115f22a4fa 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -1244,7 +1244,7 @@ done:
1244 * Finish unlinking an URB and give it back 1244 * Finish unlinking an URB and give it back
1245 */ 1245 */
1246static void uhci_giveback_urb(struct uhci_hcd *uhci, struct uhci_qh *qh, 1246static void uhci_giveback_urb(struct uhci_hcd *uhci, struct uhci_qh *qh,
1247 struct urb *urb, struct pt_regs *regs) 1247 struct urb *urb)
1248__releases(uhci->lock) 1248__releases(uhci->lock)
1249__acquires(uhci->lock) 1249__acquires(uhci->lock)
1250{ 1250{
@@ -1293,7 +1293,7 @@ __acquires(uhci->lock)
1293 } 1293 }
1294 1294
1295 spin_unlock(&uhci->lock); 1295 spin_unlock(&uhci->lock);
1296 usb_hcd_giveback_urb(uhci_to_hcd(uhci), urb, regs); 1296 usb_hcd_giveback_urb(uhci_to_hcd(uhci), urb);
1297 spin_lock(&uhci->lock); 1297 spin_lock(&uhci->lock);
1298 1298
1299 /* If the queue is now empty, we can unlink the QH and give up its 1299 /* If the queue is now empty, we can unlink the QH and give up its
@@ -1313,8 +1313,7 @@ __acquires(uhci->lock)
1313 (qh->state == QH_STATE_UNLINKING && \ 1313 (qh->state == QH_STATE_UNLINKING && \
1314 uhci->frame_number + uhci->is_stopped != qh->unlink_frame) 1314 uhci->frame_number + uhci->is_stopped != qh->unlink_frame)
1315 1315
1316static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh, 1316static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
1317 struct pt_regs *regs)
1318{ 1317{
1319 struct urb_priv *urbp; 1318 struct urb_priv *urbp;
1320 struct urb *urb; 1319 struct urb *urb;
@@ -1347,7 +1346,7 @@ static void uhci_scan_qh(struct uhci_hcd *uhci, struct uhci_qh *qh,
1347 return; 1346 return;
1348 } 1347 }
1349 1348
1350 uhci_giveback_urb(uhci, qh, urb, regs); 1349 uhci_giveback_urb(uhci, qh, urb);
1351 if (status < 0 && qh->type != USB_ENDPOINT_XFER_ISOC) 1350 if (status < 0 && qh->type != USB_ENDPOINT_XFER_ISOC)
1352 break; 1351 break;
1353 } 1352 }
@@ -1372,7 +1371,7 @@ restart:
1372 qh->is_stopped = 0; 1371 qh->is_stopped = 0;
1373 return; 1372 return;
1374 } 1373 }
1375 uhci_giveback_urb(uhci, qh, urb, regs); 1374 uhci_giveback_urb(uhci, qh, urb);
1376 goto restart; 1375 goto restart;
1377 } 1376 }
1378 } 1377 }
@@ -1487,7 +1486,7 @@ done:
1487/* 1486/*
1488 * Process events in the schedule, but only in one thread at a time 1487 * Process events in the schedule, but only in one thread at a time
1489 */ 1488 */
1490static void uhci_scan_schedule(struct uhci_hcd *uhci, struct pt_regs *regs) 1489static void uhci_scan_schedule(struct uhci_hcd *uhci)
1491{ 1490{
1492 int i; 1491 int i;
1493 struct uhci_qh *qh; 1492 struct uhci_qh *qh;
@@ -1515,7 +1514,7 @@ rescan:
1515 struct uhci_qh, node); 1514 struct uhci_qh, node);
1516 1515
1517 if (uhci_advance_check(uhci, qh)) { 1516 if (uhci_advance_check(uhci, qh)) {
1518 uhci_scan_qh(uhci, qh, regs); 1517 uhci_scan_qh(uhci, qh);
1519 if (qh->state == QH_STATE_ACTIVE) { 1518 if (qh->state == QH_STATE_ACTIVE) {
1520 uhci_urbp_wants_fsbr(uhci, 1519 uhci_urbp_wants_fsbr(uhci,
1521 list_entry(qh->queue.next, struct urb_priv, node)); 1520 list_entry(qh->queue.next, struct urb_priv, node));