Skip to contentSkip to conversation

High resolution timer for cx88 remotes

PATCH In review AH 3 participants 3 messages May 23, 2009 – Jun 17, 2009 Media (V4L/DVB)

lore
Share & tools
lore

AH

author
#0 lore raw

PATCH 1/1 High resolution timer for cx88 remotes

Hi

Some remotes requires short polling interval which in modern kernels is below resolution of standard scheduler (schedule_delayed_work), this causes problem of missed keystrokes. One of the solutions is to raise kernel timer frequency, my proposition is to use high resolution timers which are present in kernel since 2.6.16 (at least API AFAIK). I have encountered this problem on my Winfast 2000XP Expert, but after checking cx88-input.c it seems that following cards can be affected also:
WINFAST2000XP_EXPERT
WINFAST_DTV1000
WINFAST_TV2000_XP_GLOBAL
PROLINK_PLAYTVPVR
PIXELVIEW_PLAYTV_ULTRA_PRO
PROLINK_PV_8000GT
PROLINK_PV_GLOBAL_XTREME
KWORLD_LTV883
MSI_TVANYWHERE_MASTER

Patched driver seems to work on my system, with kernel 2.6.28.
I have removed kernel checks for versions below 2.6.20 - they were because of API changes in scheduler.

I have not tested it on older kernels.

Regards
AH

linux/drivers/media/video/cx88/cx88-input.c Sat May 23 14:04:17 2009 +0200 renamed from linux/drivers/media/video/cx88/cx88-input.c Sun May 17 12:28:55 2009 +0000 +0 -0
diff -r 315bc4b65b4f linux/drivers/media/video/cx88/cx88-input.c
@@ -23,10 +23,10 @@
 */

#include <linux/init.h>
-#include <linux/delay.h>
#include <linux/input.h>
#include <linux/pci.h>
#include <linux/module.h>
+#include <linux/hrtimer.h>

#include "compat.h"
#include "cx88.h"
@@ -49,7 +49,7 @@

       /* poll external decoder */
       int polling;
-       struct delayed_work work;
+       struct hrtimer timer;
       u32 gpio_addr;
       u32 last_gpio;
       u32 mask_keycode;
@@ -144,31 +144,25 @@
       }
}

-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20) -static void cx88_ir_work(void *data)
-#else
-static void cx88_ir_work(struct work_struct *work) -#endif
+enum hrtimer_restart cx88_ir_work(struct hrtimer *timer) {
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20)
- struct cx88_IR *ir = data;
-#else
- struct cx88_IR *ir = container_of(work, struct cx88_IR, work.work);
-#endif
+ unsigned long missed;
+ struct cx88_IR *ir = container_of(timer, struct cx88_IR, timer);

       cx88_ir_handle_key(ir);
-       schedule_delayed_work(&ir->work, msecs_to_jiffies(ir->polling));
+       missed = hrtimer_forward_now(&ir->timer, ktime_set(0, ir->polling * 1000000));
+       if (missed > 1)

+ ir_dprintk("Missed ticks %ld\n", missed - 1);
+
+ return HRTIMER_RESTART;
}

void cx88_ir_start(struct cx88_core *core, struct cx88_IR *ir)

{
       if (ir->polling) {

-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20)
- INIT_DELAYED_WORK(&ir->work, cx88_ir_work, ir);
-#else
- INIT_DELAYED_WORK(&ir->work, cx88_ir_work);
-#endif

-               schedule_delayed_work(&ir->work, 0);
+               hrtimer_init(&ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+               ir->timer.function = cx88_ir_work;
+               hrtimer_start(&ir->timer, ktime_set(0, ir->polling * 1000000), HRTIMER_MODE_REL);
       }
       if (ir->sampling) {
               core->pci_irqmask |= PCI_INT_IR_SMPINT;
@@ -185,7 +179,7 @@
       }

       if (ir->polling)

- cancel_delayed_work_sync(&ir->work);
+ hrtimer_cancel(&ir->timer);
}

/* ---------------------------------------------------------------------- */

#1 lore raw

Em Sat, 23 May 2009 14:06:01 +0200
AH <[email protected]> escreveu:

Quoted 67 lines

Hi

Some remotes requires short polling interval which in modern kernels is below resolution of standard scheduler (schedule_delayed_work), this causes problem of missed keystrokes. One of the solutions is to raise kernel timer frequency, my proposition is to use high resolution timers which are present in kernel since 2.6.16 (at least API AFAIK). I have encountered this problem on my Winfast 2000XP Expert, but after checking cx88-input.c it seems that following cards can be affected also:
WINFAST2000XP_EXPERT
WINFAST_DTV1000
WINFAST_TV2000_XP_GLOBAL
PROLINK_PLAYTVPVR
PIXELVIEW_PLAYTV_ULTRA_PRO
PROLINK_PV_8000GT
PROLINK_PV_GLOBAL_XTREME
KWORLD_LTV883
MSI_TVANYWHERE_MASTER

Patched driver seems to work on my system, with kernel 2.6.28. I have removed kernel checks for versions below 2.6.20 - they were because of API changes in scheduler.

I have not tested it on older kernels.

Regards
AH

diff -r 315bc4b65b4f linux/drivers/media/video/cx88/cx88-input.c
--- a/linux/drivers/media/video/cx88/cx88-input.c Sun May 17
12:28:55 2009 +0000
+++ b/linux/drivers/media/video/cx88/cx88-input.c Sat May 23
14:04:17 2009 +0200

(quoted diff) +3 -9
@@ -23,10 +23,10 @@
  */
 
 #include <linux/init.h>
-#include <linux/delay.h>
 #include <linux/input.h>
 #include <linux/pci.h>
 #include <linux/module.h>
+#include <linux/hrtimer.h>
 
 #include "compat.h"
 #include "cx88.h"

@@ -49,7 +49,7 @@
 
        /* poll external decoder */
        int polling;
-       struct delayed_work work;
+       struct hrtimer timer;
        u32 gpio_addr;
        u32 last_gpio;
        u32 mask_keycode;

@@ -144,31 +144,25 @@
        }
 }
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20)
-static void cx88_ir_work(void *data)
-#else
-static void cx88_ir_work(struct work_struct *work)
-#endif
+enum hrtimer_restart cx88_ir_work(struct hrtimer *timer)
 {
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20)
-       struct cx88_IR *ir = data;

Review line 154

Quoted 10 lines
(quoted diff) +3 -4
-#else
-       struct cx88_IR *ir = container_of(work, struct cx88_IR, work.work);
-#endif
+       unsigned long missed;
+       struct cx88_IR *ir = container_of(timer, struct cx88_IR, timer);
 
        cx88_ir_handle_key(ir);
-       schedule_delayed_work(&ir->work, msecs_to_jiffies(ir->polling));
+       missed = hrtimer_forward_now(&ir->timer, ktime_set(0, 
 ir->polling * 1000000));

Hmm... this patch got line wrapped. please fix it and re-send.

Quoted 34 lines
(quoted diff) +7 -6
+       if (missed > 1)
+               ir_dprintk("Missed ticks %ld\n", missed - 1);
+
+       return HRTIMER_RESTART;
 }
 
 void cx88_ir_start(struct cx88_core *core, struct cx88_IR *ir)
 {
        if (ir->polling) {
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20)
-               INIT_DELAYED_WORK(&ir->work, cx88_ir_work, ir);
-#else
-               INIT_DELAYED_WORK(&ir->work, cx88_ir_work);
-#endif
-               schedule_delayed_work(&ir->work, 0);
+               hrtimer_init(&ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+               ir->timer.function = cx88_ir_work;
+               hrtimer_start(&ir->timer, ktime_set(0, ir->polling * 
 1000000), HRTIMER_MODE_REL);
        }

        if (ir->sampling) {
                core->pci_irqmask |= PCI_INT_IR_SMPINT;
(quoted diff) +1 -3
@@ -185,7 +179,7 @@
        }
 
        if (ir->polling)
-               cancel_delayed_work_sync(&ir->work);
+               hrtimer_cancel(&ir->timer);
 }
 
 /* 
---------------------------------------------------------------------- */
 
--
Quoted 3 lines

To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

Cheers,
Mauro

#2 lore raw
Quoted 5 lines · Mauro Carvalho Chehab

Em Sat, 23 May 2009 14:06:01 +0200
AH <[email protected]> escreveu:

Quoted 3 lines

Patched driver seems to work on my system, with kernel 2.6.28. I have removed kernel checks for versions below 2.6.20 - they were because of API changes in scheduler.

If you are going to break compatibility below 2.6.20 then you should add the driver to versions.txt