From: Valdis.Kletnieks@vt.edu
To: Haojian Zhuang <haojian.zhuang@marvell.com>
Cc: haojian.zhuang@gmail.com, sameo@linux.intel.com,
linux-kernel@vger.kernel.org,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH 01/13] input: touchscreen: use polling mode in 88pm860x
Date: Sat, 16 Apr 2011 10:17:13 -0400 [thread overview]
Message-ID: <60599.1302963433@localhost> (raw)
In-Reply-To: Your message of "Sat, 16 Apr 2011 20:46:20 +0800." <1302957980-27343-1-git-send-email-haojian.zhuang@marvell.com>
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On Sat, 16 Apr 2011 20:46:20 +0800, Haojian Zhuang said:
> Measuring point on touchscreen with IRQ mode can only monitor pen-down
> event. If finger is moving on touchscreen, it can't be monitored by
> IRQ pen-down event. So switch to polling mode after pen-down event.
> drivers/input/touchscreen/88pm860x-ts.c | 79 ++++++++++++++++++++++++------
> +/*
> + * While 32KHz hardware timer is used for scheduler, we always assign HZ
> + * to 128. It means that 1 tick costs 7.8msec.
> + */
> +#define MEASURE_INTERVAL_MS (7)
Is it guaranteed that this hardware part will only ever be used on systems
where this is true? How big a bug would it be if somebody tried to glue this
touchscreen into some random embedded-ARM where HZ was something else, and
should this be computed as a function of HZ instead of hardcoding 7?
It *looks* like the intent of the schedule_delayed_work() call is "let's run
this once a tick when we're awake *anyhow*" - but looking at the code, I can't
convince myself a rounding error in computing 'interval' won't schedule 1ms
before or after the next tick would have been. Isn't there a better API with
slack timers or something that would do a better "next tick" job?
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next prev parent reply other threads:[~2011-04-16 14:17 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2011041301>
2011-04-13 14:50 ` 1. Replace mfd_data with platform_data for 88pm860x since mfd tree is upgraded Haojian Zhuang
2011-04-13 14:50 ` [PATCH 01/13] input: touchscreen: use polling mode in 88pm860x Haojian Zhuang
2011-04-13 14:50 ` [PATCH 02/13] input: touchscreen: move initialization " Haojian Zhuang
2011-04-13 14:50 ` [PATCH 03/13] rtc: add 88pm860x rtc Haojian Zhuang
2011-04-13 14:50 ` [PATCH 04/13] input: set the long press detection in 88pm860x onkey Haojian Zhuang
2011-04-13 14:50 ` [PATCH 05/13] w1: add DS278x slave driver Haojian Zhuang
2011-04-13 14:50 ` [PATCH 06/13] mfd: pxa-w1: MFD driver for PXA 1wire control + DS1WM chip Haojian Zhuang
2011-04-13 14:50 ` [PATCH 07/13] mfd: fix build warning on 88pm860x Haojian Zhuang
2011-04-13 14:50 ` [PATCH 08/13] mfd: use platform_data in max8925 Haojian Zhuang
2011-04-13 14:51 ` [PATCH 09/13] input: get irq from resource in max8925 onkey Haojian Zhuang
2011-04-13 14:51 ` [PATCH 10/13] rtc: avoid to use hardcoding irq number in max8925 Haojian Zhuang
2011-04-13 14:51 ` [PATCH 11/13] power_supply: max8925: use platform_data from cell Haojian Zhuang
2011-04-13 14:51 ` [PATCH 12/13] regulator: check name in initialization of max8925 Haojian Zhuang
2011-04-13 14:51 ` [PATCH 13/13] regulator: max8925: enable i2c sequence for control Haojian Zhuang
2011-04-16 18:02 ` Mark Brown
2011-04-16 18:01 ` [PATCH 12/13] regulator: check name in initialization of max8925 Mark Brown
2011-04-18 13:49 ` Haojian Zhuang
2011-04-13 15:03 ` [PATCH 11/13] power_supply: max8925: use platform_data from cell Anton Vorontsov
2011-04-14 2:26 ` Haojian Zhuang
2011-04-14 2:16 ` Haojian Zhuang
2011-04-15 0:41 ` [PATCH 10/13] rtc: avoid to use hardcoding irq number in max8925 Wanlong Gao
2011-04-15 0:35 ` [PATCH 08/13] mfd: use platform_data " Wanlong Gao
2011-04-14 14:17 ` [PATCH 06/13] mfd: pxa-w1: MFD driver for PXA 1wire control + DS1WM chip Wanlong Gao
2011-04-14 14:21 ` Haojian Zhuang
2011-04-14 14:29 ` Wanlong Gao
2011-04-14 14:02 ` [PATCH 01/13] input: touchscreen: use polling mode in 88pm860x Wanlong Gao
2011-04-14 14:41 ` Haojian Zhuang
2011-04-14 14:52 ` Wanlong Gao
2011-04-16 12:46 ` Haojian Zhuang
2011-04-16 13:17 ` Wanlong Gao
2011-04-16 14:17 ` Valdis.Kletnieks [this message]
2011-04-18 13:12 ` Haojian Zhuang
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