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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/input/touchscreen/h3600_ts_input.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/input/touchscreen/h3600_ts_input.c')
-rw-r--r--drivers/input/touchscreen/h3600_ts_input.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/drivers/input/touchscreen/h3600_ts_input.c b/drivers/input/touchscreen/h3600_ts_input.c
index e2b910018773..d9e61ee05ea9 100644
--- a/drivers/input/touchscreen/h3600_ts_input.c
+++ b/drivers/input/touchscreen/h3600_ts_input.c
@@ -106,19 +106,18 @@ struct h3600_dev {
106 char phys[32]; 106 char phys[32];
107}; 107};
108 108
109static irqreturn_t action_button_handler(int irq, void *dev_id, struct pt_regs *regs) 109static irqreturn_t action_button_handler(int irq, void *dev_id)
110{ 110{
111 int down = (GPLR & GPIO_BITSY_ACTION_BUTTON) ? 0 : 1; 111 int down = (GPLR & GPIO_BITSY_ACTION_BUTTON) ? 0 : 1;
112 struct input_dev *dev = (struct input_dev *) dev_id; 112 struct input_dev *dev = (struct input_dev *) dev_id;
113 113
114 input_regs(dev, regs);
115 input_report_key(dev, KEY_ENTER, down); 114 input_report_key(dev, KEY_ENTER, down);
116 input_sync(dev); 115 input_sync(dev);
117 116
118 return IRQ_HANDLED; 117 return IRQ_HANDLED;
119} 118}
120 119
121static irqreturn_t npower_button_handler(int irq, void *dev_id, struct pt_regs *regs) 120static irqreturn_t npower_button_handler(int irq, void *dev_id)
122{ 121{
123 int down = (GPLR & GPIO_BITSY_NPOWER_BUTTON) ? 0 : 1; 122 int down = (GPLR & GPIO_BITSY_NPOWER_BUTTON) ? 0 : 1;
124 struct input_dev *dev = (struct input_dev *) dev_id; 123 struct input_dev *dev = (struct input_dev *) dev_id;
@@ -127,7 +126,6 @@ static irqreturn_t npower_button_handler(int irq, void *dev_id, struct pt_regs *
127 * This interrupt is only called when we release the key. So we have 126 * This interrupt is only called when we release the key. So we have
128 * to fake a key press. 127 * to fake a key press.
129 */ 128 */
130 input_regs(dev, regs);
131 input_report_key(dev, KEY_SUSPEND, 1); 129 input_report_key(dev, KEY_SUSPEND, 1);
132 input_report_key(dev, KEY_SUSPEND, down); 130 input_report_key(dev, KEY_SUSPEND, down);
133 input_sync(dev); 131 input_sync(dev);
@@ -165,14 +163,12 @@ unsigned int h3600_flite_power(struct input_dev *dev, enum flite_pwr pwr)
165 * packets. Some packets coming from serial are not touchscreen related. In 163 * packets. Some packets coming from serial are not touchscreen related. In
166 * this case we send them off to be processed elsewhere. 164 * this case we send them off to be processed elsewhere.
167 */ 165 */
168static void h3600ts_process_packet(struct h3600_dev *ts, struct pt_regs *regs) 166static void h3600ts_process_packet(struct h3600_dev *ts)
169{ 167{
170 struct input_dev *dev = ts->dev; 168 struct input_dev *dev = ts->dev;
171 static int touched = 0; 169 static int touched = 0;
172 int key, down = 0; 170 int key, down = 0;
173 171
174 input_regs(dev, regs);
175
176 switch (ts->event) { 172 switch (ts->event) {
177 /* 173 /*
178 Buttons - returned as a single byte 174 Buttons - returned as a single byte
@@ -301,7 +297,7 @@ static int state;
301#define STATE_EOF 3 /* state where we decode checksum or EOF */ 297#define STATE_EOF 3 /* state where we decode checksum or EOF */
302 298
303static irqreturn_t h3600ts_interrupt(struct serio *serio, unsigned char data, 299static irqreturn_t h3600ts_interrupt(struct serio *serio, unsigned char data,
304 unsigned int flags, struct pt_regs *regs) 300 unsigned int flags)
305{ 301{
306 struct h3600_dev *ts = serio_get_drvdata(serio); 302 struct h3600_dev *ts = serio_get_drvdata(serio);
307 303
@@ -333,7 +329,7 @@ static irqreturn_t h3600ts_interrupt(struct serio *serio, unsigned char data,
333 case STATE_EOF: 329 case STATE_EOF:
334 state = STATE_SOF; 330 state = STATE_SOF;
335 if (data == CHAR_EOF || data == ts->chksum) 331 if (data == CHAR_EOF || data == ts->chksum)
336 h3600ts_process_packet(ts, regs); 332 h3600ts_process_packet(ts);
337 break; 333 break;
338 default: 334 default:
339 printk("Error3\n"); 335 printk("Error3\n");