From: Peter Ujfalusi <peter.ujfalusi@ti.com>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Linus Walleij <linus.walleij@linaro.org>,
linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCH] gpio: twl4030: Correct status reporting when the GPIO is used as output
Date: Thu, 6 Dec 2012 11:55:00 +0100 [thread overview]
Message-ID: <50C07984.8000003@ti.com> (raw)
In-Reply-To: <20121205224813.584123E0E22@localhost>
On 12/05/2012 11:48 PM, Grant Likely wrote:
>> - base = REG_GPIODATAIN1 + d_bnk;
>> + direction = gpio_twl4030_read(REG_GPIODATADIR1 + d_bnk);
>> + if (direction > 0 && (direction >> d_off) & 0x1)
>> + base = REG_SETGPIODATAOUT1 + d_bnk;
>> + else
>> + base = REG_GPIODATAIN1 + d_bnk;
>> +
>
> This is probably quite expensive considering that reads need to go out
> the i2c bus. Things like the output state and the pin direction should
> be cached by the driver in its private data structure so that you don't
> add an additional i2c round trip.
True. I have sent the v2, which grown a bit since I did not wanted to add more
global variable to this driver.
--
Péter
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prev parent reply other threads:[~2012-12-06 10:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-05 9:49 [PATCH] gpio: twl4030: Correct status reporting when the GPIO is used as output Peter Ujfalusi
2012-12-05 22:48 ` Grant Likely
2012-12-06 10:55 ` Peter Ujfalusi [this message]
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