From: Trilok Soni <tsoni@codeaurora.org>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Philippe Langlais <philippe.langlais@stericsson.com>,
linux-input@vger.kernel.org,
STEricsson_nomadik_linux@list.st.com
Subject: Re: [PATCH] input: replace request_irq by request_any_context_irq in keyboard GPIO driver
Date: Thu, 20 Jan 2011 14:26:30 +0530 [thread overview]
Message-ID: <4D37F8BE.8040005@codeaurora.org> (raw)
In-Reply-To: <20110120081319.GC2498@core.coreip.homeip.net>
Hi Dmitry,
On 1/20/2011 1:43 PM, Dmitry Torokhov wrote:
>>>
>>> No, this it not correct. request_any_context_irq() means that you could
>>> either get a hardirq or a treaded one. However above you are changing to
>>> gpio_get_value_cansleep() which indicates that you can sleep.
>>>
>>> You need to either revert to gpio_get_value() or explicitly request
>>> threaded IRQ.
>>
>> This could be problem. Say, we are doing request_any_context_irq(..) and gpio is over slow-bus,
>> so we naturally get into the threaded code, and in the thread handler we are calling gpio_get_value(..),
>> but in this case gpio_get_value could throw a warning that we should call gpio_get_value_cansleep(...)
>> because sleep attribute is added into the gpiolib hook implementation for these gpios.
>>
>> Now suppose gpio is memory mapped and we enter into the hardirq and calling sleep variant into the
>> handler code will be naturally bad.
>>
>> How about checking maysleep explicitly here while using the request_any_context_irq() call though
>> the semantics of gpiolib framework discourages that.
>>
>
> Any drawbacks for explicitly switching to threaded IRQ and keeping
> gpio_get_value_cansleep()? (That was the 2nd option I mentioned BTW).
>
Only drawback is that you get "dedicated thread" in case the irqs are not chained handler. In worst-case
it would introduce the latencies otherwise fine.
---Trilok Soni
--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
next prev parent reply other threads:[~2011-01-20 8:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-12 9:41 Changes in keyboard GPIO driver Philippe Langlais
2011-01-12 9:41 ` [PATCH] input: replace request_irq by request_any_context_irq " Philippe Langlais
2011-01-20 7:53 ` Dmitry Torokhov
2011-01-20 8:00 ` Trilok Soni
2011-01-20 8:13 ` Dmitry Torokhov
2011-01-20 8:56 ` Trilok Soni [this message]
2011-01-20 9:23 ` Rabin Vincent
2011-01-20 10:04 ` Dmitry Torokhov
2011-01-20 12:14 ` Philippe Langlais
2011-01-21 7:10 ` Dmitry Torokhov
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