From mboxrd@z Thu Jan  1 00:00:00 1970
From: bmeneguele@gmail.com (Bruno E. O. Meneguele)
Date: Sat, 30 Sep 2017 09:05:46 -0300
Subject: Input device driver
In-Reply-To: <20170930074208.GA13070@kroah.com>
References: <20170929223849.GA18392@glitch>
	<45189.1506726543@turing-police.cc.vt.edu>
	<20170930001905.GA9452@glitch> <20170930074208.GA13070@kroah.com>
Message-ID: <20170930120546.GB9452@glitch>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On 30-09, Greg KH wrote:
> On Fri, Sep 29, 2017 at 09:19:05PM -0300, Bruno E. O. Meneguele wrote:
> > On 29-09, valdis.kletnieks at vt.edu wrote:
> > > On Fri, 29 Sep 2017 19:38:49 -0300, "Bruno E. O. Meneguele" said:
> > > 
> > > > 2) I'm using a USB keyboard as the testing device, and TBH I got
> > > > confused if I could actually use the input subsystem for that or I
> > > > _should_ use HID instead (considering the keyboard is HID compliant).
> > > 
> > > Step 0: Decide if you're writing an interrupt handling driver, a USB driver, or
> > > an HID driver - the three live at different levels of abstraction, and
> > > confusing them will also confuse both you and your kernel.
> > > 
> > 
> > I don't know why I didn't realize earlier the two counterparts:
> > interruption vs USB, USB devices are handled in polling mode, not
> > with IRQs.
> 
> It's not that simple.  USB devices only work when the host asks them for
> data, so yes, that can be called "polling", but on the host (i.e. your
> computer), IRQs are used to get the data from the USB host controller.
> The USB driver is notified with the data from the mouse in IRQ context,
> so you do have to be aware of IRQ issues when dealing with USB devices.
> 

Ah ok, I understand. Considering I'm going to write an USB device now
I'll dive in LDD3 and other docs to better understand USB subsystem.

Thank you very much for this clarification gregkh. 

> best of luck,
> 

Thanks! :) I hope be back "soon" with some progress.

-- 
bmeneg 
PGP Key: http://bmeneg.com/pubkey.txt
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