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

Kevin Baradon
2013-03-17T15:07:09Z

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

> Em Sun, 24 Feb 2013 21:19:29 +0100
> Kevin Baradon <kevin.baradon@gmail.com> 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@gmail.com>
> > ---
> > 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@gmail.com>
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@gmail.com>
---
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