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From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Cc: H Hartley Sweeten <hartleys@visionengravers.com>,
	linux-input@vger.kernel.org,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-arm-kernel-infradead <linux-arm-kernel@lists.infradead.org>,
	Sascha linux-arm <s.hauer@pengutronix.de>
Subject: Re: [PATCH v2] input: MXC: add mxc-keypad driver to support the Keypad Port present in the mxc application processors family.
Date: Tue, 26 Jan 2010 01:52:17 -0800	[thread overview]
Message-ID: <20100126095217.GC3480@core.coreip.homeip.net> (raw)
In-Reply-To: <1263664125.4350.18.camel@realization>

Hi Alberto,

On Sat, Jan 16, 2010 at 06:48:45PM +0100, Alberto Panizzo wrote:
> Version 2 for this driver proposal.
> --------------------------------------------------------------------------------
> The MXC family of Application Processors is shipped with a Keypad Port 
> supported now by this driver.
> 
> The peripheral can control up to an 8x8 matrix key pad where all the scanning 
> procedure is done via software.
> 
> The hardware provide two interrupts: one for a key pressed (KDI) and one for 
> all key releases (KRI). There is also a simple circuit for glitch reduction 
> (said for synchronization) made by two series of 3 D-latches clocked by the 
> keypad-clock that stabilize the interrupts sources.
> KDI and KRI are fired only if the respective conditions are maintained for at 
> last 4 keypad-clock cycle.
> 
> Those simple synchronization circuits are used also for multiple key pressures: 
> between a KDI and a KRI the driver reset the sync circuit and re-enable the KDI
> interrupt so after 3 keypad-clock cycle another KDI is fired making possible to
> repeat the matrix scan operation.
> 

Nicely looking driver, thank you.

> This algorithm is done via a threaded management of the keypad interrupt source
> and delayed by a proper (and longer) debounce interval controlled by the 
> platform initialization.

This I am not so sure about - the core of the matrix scan routine does
not sleep so I wonder if starting a separate thread is not too wasteful
in this case - you can easily do whan you want with a timer, no?

> +
> +	/*
> +	 * Search for rows and cols enabled
> +	 */
> +	keymap_data = (struct matrix_keymap_data *) pdata->keymap_data;

Why do you need to cast away constness instead of declaring keymap_data
as const pointer?

-- 
Dmitry

WARNING: multiple messages have this Message-ID
From: dmitry.torokhov@gmail.com (Dmitry Torokhov)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] input: MXC: add mxc-keypad driver to support the Keypad Port present in the mxc application processors family.
Date: Tue, 26 Jan 2010 01:52:17 -0800	[thread overview]
Message-ID: <20100126095217.GC3480@core.coreip.homeip.net> (raw)
In-Reply-To: <1263664125.4350.18.camel@realization>

Hi Alberto,

On Sat, Jan 16, 2010 at 06:48:45PM +0100, Alberto Panizzo wrote:
> Version 2 for this driver proposal.
> --------------------------------------------------------------------------------
> The MXC family of Application Processors is shipped with a Keypad Port 
> supported now by this driver.
> 
> The peripheral can control up to an 8x8 matrix key pad where all the scanning 
> procedure is done via software.
> 
> The hardware provide two interrupts: one for a key pressed (KDI) and one for 
> all key releases (KRI). There is also a simple circuit for glitch reduction 
> (said for synchronization) made by two series of 3 D-latches clocked by the 
> keypad-clock that stabilize the interrupts sources.
> KDI and KRI are fired only if the respective conditions are maintained for at 
> last 4 keypad-clock cycle.
> 
> Those simple synchronization circuits are used also for multiple key pressures: 
> between a KDI and a KRI the driver reset the sync circuit and re-enable the KDI
> interrupt so after 3 keypad-clock cycle another KDI is fired making possible to
> repeat the matrix scan operation.
> 

Nicely looking driver, thank you.

> This algorithm is done via a threaded management of the keypad interrupt source
> and delayed by a proper (and longer) debounce interval controlled by the 
> platform initialization.

This I am not so sure about - the core of the matrix scan routine does
not sleep so I wonder if starting a separate thread is not too wasteful
in this case - you can easily do whan you want with a timer, no?

> +
> +	/*
> +	 * Search for rows and cols enabled
> +	 */
> +	keymap_data = (struct matrix_keymap_data *) pdata->keymap_data;

Why do you need to cast away constness instead of declaring keymap_data
as const pointer?

-- 
Dmitry

  parent reply	other threads:[~2010-01-26  9:52 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-08 18:58 MXC: input: add mxc-keypad driver to support the keypad interface " Alberto Panizzo
2010-01-08 18:58 ` Alberto Panizzo
2010-01-08 20:33 ` H Hartley Sweeten
2010-01-08 20:33   ` H Hartley Sweeten
2010-01-08 20:33   ` H Hartley Sweeten
2010-01-16 17:48   ` [PATCH v2] input: MXC: add mxc-keypad driver to support the Keypad Port " Alberto Panizzo
2010-01-16 17:48     ` Alberto Panizzo
2010-01-21 16:17     ` Alberto Panizzo
2010-01-21 16:17       ` Alberto Panizzo
2010-01-23 10:46     ` Alberto Panizzo
2010-01-23 10:46       ` Alberto Panizzo
2010-01-23 10:46       ` Alberto Panizzo
2010-01-26  9:52     ` Dmitry Torokhov [this message]
2010-01-26  9:52       ` Dmitry Torokhov
2010-01-26 10:29       ` Alberto Panizzo
2010-01-26 10:29         ` Alberto Panizzo

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