From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755441AbcBEREt (ORCPT ); Fri, 5 Feb 2016 12:04:49 -0500 Received: from mail-pf0-f178.google.com ([209.85.192.178]:36341 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755230AbcBEREr (ORCPT ); Fri, 5 Feb 2016 12:04:47 -0500 Message-ID: <56B4D62A.2020904@gmail.com> Date: Fri, 05 Feb 2016 22:34:42 +0530 From: Sudip Mukherjee User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Takashi Iwai CC: Jaroslav Kysela , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] portman2x4 - use new parport device model References: <1454603903-15967-1-git-send-email-sudipm.mukherjee@gmail.com> <1454603903-15967-3-git-send-email-sudipm.mukherjee@gmail.com> <20160205061706.GA6374@sudip-pc> <56B4D2EB.4060006@gmail.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 05 February 2016 10:31 PM, Takashi Iwai wrote: > On Fri, 05 Feb 2016 17:50:51 +0100, > Sudip Mukherjee wrote: >> >> On Friday 05 February 2016 05:25 PM, Takashi Iwai wrote: >>> On Fri, 05 Feb 2016 07:17:06 +0100, >>> Sudip Mukherjee wrote: >>>> >>>> On Thu, Feb 04, 2016 at 05:51:07PM +0100, Takashi Iwai wrote: >>>>> On Thu, 04 Feb 2016 17:38:23 +0100, >>>>> Sudip Mukherjee wrote: >>>>>> >>>>>> Modify portman driver to use the new parallel port device model. >>>>>> The advantage of using the device model is that the device gets binded >>>>>> to the hardware, we get the feature of hotplug, we can bind/unbind >>>>>> the driver at runtime. >>>>>> The only change is in the way the driver gets registered with the >>>>>> parallel port subsystem and so as a result there is no user visible >>>>>> change or any chance of regression. >>>>>> >>>>>> Signed-off-by: Sudip Mukherjee >>>>>> --- >>>>>> >>>>>> v3: changed commit message >>>>>> v2: >>>>>> 1. pardev_cb is initialized while declaring, thus removing the use of >>>>>> memset. >>>>>> 2. used pdev->id. >>>>>> 3. v1 did not have the parport probe callback, but >>>>>> we will need the probe callback for binding as the name of the driver >>>>>> and the name of the device is different. >>>>>> 4. in v1 I missed modifying snd_portman_probe_port(). >>>>>> >>>>>> sound/drivers/portman2x4.c | 53 ++++++++++++++++++++++++++++++++++------------ >>>>>> 1 file changed, 39 insertions(+), 14 deletions(-) >>>>>> >>>>>> diff --git a/sound/drivers/portman2x4.c b/sound/drivers/portman2x4.c >>>>>> index 172685d..a22f56c 100644 >>>>>> --- a/sound/drivers/portman2x4.c >>>>>> +++ b/sound/drivers/portman2x4.c >>>>>> @@ -650,10 +650,21 @@ static int snd_portman_probe_port(struct parport *p) >>>>>> { >>>>>> struct pardevice *pardev; >>>>>> int res; >>>>>> - >>>>>> - pardev = parport_register_device(p, DRIVER_NAME, >>>>>> - NULL, NULL, NULL, >>>>>> - 0, NULL); >>>>>> + struct pardev_cb pdev_cb = { >>>>>> + .preempt = NULL, >>>>>> + .wakeup = NULL, >>>>>> + .private = NULL, >>>>>> + .irq_func = NULL, >>>>>> + .flags = 0, >>>>>> + }; >>>>>> + >>>>>> + /* >>>>>> + * Specify the device number as SNDRV_CARDS + 1 so that the >>>>>> + * device id alloted to this temporary device will never clash >>>>>> + * with an actual device already registered. >>>>>> + */ >>>>>> + pardev = parport_register_dev_model(p, DRIVER_NAME, &pdev_cb, >>>>>> + SNDRV_CARDS + 1); >>>>> >>>>> Hmm, doesn't this result in a device name like "xxx.33" ? >>>> >>>> yes, it will. But this is a temoporary device just to check if the >>>> sound card is connected to that particular parallel port or not. After >>>> checking this device is immediately unregistered. My idea here was to >>>> have a device number which will never clash with another device number. >>>> And we can never have a device like "xxx.33", so no conflict. :) >>> >>> Ah, this is the temporary one. If so, does it make sense to convert >>> this to dev_model one? This means that the device will be notified to >>> udev even though this is a temporary one to be removed immediately. >> >> But since we are registering a device it should ideally follow the >> dev_model. > > We shouldn't advertise the device that shouldn't be handled by the > user-space. The device you're trying to register there is the one > that lives only shortly just for probing the address. > > >>> It's what we'd want to avoid. The function serves just as probing the >>> availability of the given port, not really registering anything >>> there. >> >> To my understanding, it is probing for the availability of the port and >> it is also calling portman_probe() which is initializing hardware >> handshake lines to midi box and checking if the portman card is >> connected to that parallel port or not. >> >>> >>> That is, we need to change the registration flow itself if we really >>> want to move dev_model for the whole. >> >> Any hint, how to register then? >> Without probing (reading and writing to that port) I can not know if >> that port is having the card and to use the port I need to register a >> device with that port. > > Just returning the error at probe of the parport device itself instead > of doing the probe twice? The current way is racy in anyway. Ohhhk.. so we only register once and if we find the card - we continue, we donot find the card then we unregister the device and return error code. Great. I will send you a patch for your review. Regards Sudip