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@xxxxxx 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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