From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Tissoires Subject: Re: Help writing a custom HID driver Date: Thu, 6 Nov 2014 15:22:00 -0500 Message-ID: References: <545BBF05.9030203@mediacru.sh> <545BCBE9.6040309@mediacru.sh> <545BD794.7090002@mediacru.sh> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-qc0-f179.google.com ([209.85.216.179]:64263 "EHLO mail-qc0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751020AbaKFUWC (ORCPT ); Thu, 6 Nov 2014 15:22:02 -0500 Received: by mail-qc0-f179.google.com with SMTP id o8so1433448qcw.24 for ; Thu, 06 Nov 2014 12:22:00 -0800 (PST) In-Reply-To: <545BD794.7090002@mediacru.sh> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Jose Diez Cc: linux-input On Thu, Nov 6, 2014 at 3:18 PM, Jose Diez wrote: > Okay, so I've solved the watchdog issue, and now I want the driver to be > loaded automatically. I've copied the module to /lib/modules// and > run depmod -a, and I can see it in modules.alias, but it looks like > hid_generic grabs it first upon boot - my module is loaded correctly, but it > doesn't grab the HID device. > > If I `modprobe -r hid_generic` and then load my module, everything works > correctly. Yep. You need to add your device VendorID/ProductID in hid_have_special_driver[] in hid-core.c. This will tell hid-generic not to grab your device, and your custom module will take over. Cheers, Benjamin > > On 06/11/14 19:28, Jose Diez wrote: >> >> Thanks Benjamin. That fixed the issue. Have a great day. >> >> On 06/11/14 18:57, Benjamin Tissoires wrote: >>> >>> Hi Jose, >>> >>> On Thu, Nov 6, 2014 at 1:33 PM, Jose Diez wrote: >>>> >>>> Hello linux-input, >>>> >>>> I'm trying to write a custom HID driver. It works fine, and I can send >>>> reports just fine, but one of the requirements of this device is that I >>>> have >>>> to reply to reports with code 62 with another report with code 62, which >>>> resets a watchdog in the device. >>>> >>>> This is my code so far: http://codepad.org/m4QiWhDt >>>> >>>> The problem is in line 40. It seems like I'm not allowed to call >>>> hid_hw_output_report from the raw_event callback handler. I've tried >>>> surrounding the call with spin_locks, but I still get the "scheduling >>>> while >>>> atomic" error. >>> >>> Yeah, when you are in the .event callback, you are basically called by >>> an IRQ, so you can not schedule a potentially blocking operation. >>> >>>> I'm not sure how to approach this - can someone help? It would be much >>>> appreciated. Thanks. >>> >>> I would use a worker to do what you are trying to do. You can have a >>> look at the reset_worker we have in drivers/hid/hid-rmi.c. >>> When the event is not one we expected, we schedule a worker thread >>> which then sends an output report to the device. This way, the >>> blocking operation is sent from a different thread than the IRQ one. >>> It is kind of what you are willing to do. >>> There are many other examples of workers in the hid subtree, or you >>> can refer to the doc to find out more. >>> >>> Cheers, >>> Benjamin >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-input" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-input" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >