Re: [PATCH 1/2] media/rc/imon.c: make send_packet() delay configurable

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Le Thu, 14 Mar 2013 12:01:53 -0300,
Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> a écrit :

> Em Sun, 24 Feb 2013 21:19:29 +0100
> Kevin Baradon <kevin.baradon@xxxxxxxxx> escreveu:
> 
> > Some imon devices (like 15c2:0036) need a higher delay between send_packet calls.
> > Default value is still 5ms to avoid regressions on already working hardware.
> > 
> > Also use interruptible wait to avoid load average going too high (and let caller handle signals).
> > 
> > Signed-off-by: Kevin Baradon <kevin.baradon@xxxxxxxxx>
> > ---
> >  drivers/media/rc/imon.c |   14 +++++++++++---
> >  1 file changed, 11 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
> > index 78d109b..a3e66a0 100644
> > --- a/drivers/media/rc/imon.c
> > +++ b/drivers/media/rc/imon.c
> > @@ -347,6 +347,11 @@ module_param(pad_stabilize, int, S_IRUGO | S_IWUSR);
> >  MODULE_PARM_DESC(pad_stabilize, "Apply stabilization algorithm to iMON PAD "
> >  		 "presses in arrow key mode. 0=disable, 1=enable (default).");
> >  
> > +static unsigned int send_packet_delay = 5;
> > +module_param(send_packet_delay, uint, S_IRUGO | S_IWUSR);
> > +MODULE_PARM_DESC(send_packet_delay, "Minimum delay between send_packet() calls "
> > +		 "(default 5ms)");
> > +
> 
> Users will find a hard time discovering what delay is needed for each device.
> 
> If this is a per-device type property, then it should, instead, be associated
> with the device's USB ID.
> 
> The better would be to encapsulate it at the USB device table, like adding a
> NEED_(extra)_DELAY flag, like:
> 
> 	{ USB_DEVICE(0x15c2, 0x0036),  .driver_info = NEED_10MS_DELAY },
> 
> If such flag is zero (like on all devices where .driver_info is not filled, as
> Kernel zeroes the memory on all static vars), then it will keep using 5ms.
> 
> Another alternative would be to use .driver_info for the device type, and
> add a logic to handle different types with different logic. This is what
> mceusb.c does, for example.
> 

Hi,

Please find below an updated patch:


>From 8d4ba61cb21617b8169127b085332ed7813470c9 Mon Sep 17 00:00:00 2001
From: Kevin Baradon <kevin.baradon@xxxxxxxxx>
Date: Mon, 18 Feb 2013 18:42:47 +0100
Subject: [PATCH 1/2] media/rc/imon.c: make send_packet() delay larger for 15c2:0036

Imon device 15c2:0036 need a higher delay between send_packet() calls.
Also use interruptible wait to avoid load average going too high (and let caller handle signals).

Signed-off-by: Kevin Baradon <kevin.baradon@xxxxxxxxx>
---
 drivers/media/rc/imon.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
index dec203b..178b946 100644
--- a/drivers/media/rc/imon.c
+++ b/drivers/media/rc/imon.c
@@ -112,6 +112,7 @@ struct imon_context {
 	bool tx_control;
 	unsigned char usb_rx_buf[8];
 	unsigned char usb_tx_buf[8];
+	unsigned int send_packet_delay;
 
 	struct tx_t {
 		unsigned char data_buf[35];	/* user data buffer */
@@ -185,6 +186,10 @@ enum {
 	IMON_KEY_PANEL	= 2,
 };
 
+enum {
+	IMON_NEED_20MS_PKT_DELAY = 1
+};
+
 /*
  * USB Device ID for iMON USB Control Boards
  *
@@ -215,7 +220,7 @@ static struct usb_device_id imon_usb_id_table[] = {
 	/* SoundGraph iMON OEM Touch LCD (IR & 4.3" VGA LCD) */
 	{ USB_DEVICE(0x15c2, 0x0035) },
 	/* SoundGraph iMON OEM VFD (IR & VFD) */
-	{ USB_DEVICE(0x15c2, 0x0036) },
+	{ USB_DEVICE(0x15c2, 0x0036), .driver_info = IMON_NEED_20MS_PKT_DELAY },
 	/* device specifics unknown */
 	{ USB_DEVICE(0x15c2, 0x0037) },
 	/* SoundGraph iMON OEM LCD (IR & LCD) */
@@ -535,12 +540,12 @@ static int send_packet(struct imon_context *ictx)
 	kfree(control_req);
 
 	/*
-	 * Induce a mandatory 5ms delay before returning, as otherwise,
+	 * Induce a mandatory delay before returning, as otherwise,
 	 * send_packet can get called so rapidly as to overwhelm the device,
 	 * particularly on faster systems and/or those with quirky usb.
 	 */
-	timeout = msecs_to_jiffies(5);
-	set_current_state(TASK_UNINTERRUPTIBLE);
+	timeout = msecs_to_jiffies(ictx->send_packet_delay);
+	set_current_state(TASK_INTERRUPTIBLE);
 	schedule_timeout(timeout);
 
 	return retval;
@@ -2335,6 +2340,10 @@ static int imon_probe(struct usb_interface *interface,
 
 	}
 
+	/* default send_packet delay is 5ms but some devices need more */
+	ictx->send_packet_delay = id->driver_info & IMON_NEED_20MS_PKT_DELAY ?
+				  20 : 5;
+
 	usb_set_intfdata(interface, ictx);
 
 	if (ifnum == 0) {
-- 
1.7.10.4


> >  /*
> >   * In certain use cases, mouse mode isn't really helpful, and could actually
> >   * cause confusion, so allow disabling it when the IR device is open.
> > @@ -535,12 +540,15 @@ static int send_packet(struct imon_context *ictx)
> >  	kfree(control_req);
> >  
> >  	/*
> > -	 * Induce a mandatory 5ms delay before returning, as otherwise,
> > +	 * Induce a mandatory delay before returning, as otherwise,
> >  	 * send_packet can get called so rapidly as to overwhelm the device,
> >  	 * particularly on faster systems and/or those with quirky usb.
> > +	 * Do not use TASK_UNINTERRUPTIBLE as this routine is called quite often
> > +	 * and doing so will increase load average slightly. Caller will handle
> > +	 * signals itself.
> >  	 */
> > -	timeout = msecs_to_jiffies(5);
> > -	set_current_state(TASK_UNINTERRUPTIBLE);
> > +	timeout = msecs_to_jiffies(send_packet_delay);
> > +	set_current_state(TASK_INTERRUPTIBLE);
> >  	schedule_timeout(timeout);
> >  
> >  	return retval;
> 
> Regards,
> Mauro

Regards,
Kevin

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