Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757887Ab3CNPCD (ORCPT ); Thu, 14 Mar 2013 11:02:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12283 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757777Ab3CNPCA (ORCPT ); Thu, 14 Mar 2013 11:02:00 -0400 Date: Thu, 14 Mar 2013 12:01:53 -0300 From: Mauro Carvalho Chehab To: Kevin Baradon Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Jarod Wilson Subject: Re: [PATCH 1/2] media/rc/imon.c: make send_packet() delay configurable Message-ID: <20130314120153.7bb71ad8@redhat.com> In-Reply-To: <1361737170-4687-2-git-send-email-kevin.baradon@gmail.com> References: <1361737170-4687-1-git-send-email-kevin.baradon@gmail.com> <1361737170-4687-2-git-send-email-kevin.baradon@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3036 Lines: 74 Em Sun, 24 Feb 2013 21:19:29 +0100 Kevin Baradon 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 > --- > 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. > /* > * 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/