linux-kernel - Re: [PATCH v2 3/3] ALSA: hda: add support for Huawei WMI MicMute LED

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Date:   Fri, 2 Nov 2018 20:33:38 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Ayman Bagabas <ayman.bagabas@...il.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Hui Wang <hui.wang@...onical.com>,
        Andy Shevchenko <andy@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        Jaroslav Kysela <perex@...ex.cz>, kailang@...ltek.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] ALSA: hda: add support for Huawei WMI MicMute LED

On Fri, Nov 2, 2018 at 8:30 PM Takashi Iwai <tiwai@...e.de> wrote:
> On Fri, 02 Nov 2018 19:12:44 +0100,
> Andy Shevchenko wrote:
> >
> > > +       if (action == HDA_FIXUP_ACT_PROBE) {
> > > +               if (!huawei_wmi_micmute_led_set_func)
> > > +                       huawei_wmi_micmute_led_set_func = symbol_request(huawei_wmi_micmute_led_set);
> > > +               if (!huawei_wmi_micmute_led_set_func) {
> > > +                       codec_warn(codec, "Failed to find huawei_wmi symbol huawei_wmi_micmute_led_set\n");
> > > +                       return;
> > > +               }
> > > +               removefunc = (huawei_wmi_micmute_led_set_func(false) < 0)
> > > +                       || (snd_hda_gen_add_micmute_led(codec, update_huawei_wmi_micmute_led) < 0);
> > > +
> > > +       }
> > > +
> > > +       if (huawei_wmi_micmute_led_set_func && (action == HDA_FIXUP_ACT_FREE || removefunc)) {
> > > +               symbol_put(huawei_wmi_micmute_led_set);
> > > +               huawei_wmi_micmute_led_set_func = NULL;
> > > +       }
> > > +}
> >
> > Takashi, is it a way how the rest sound drivers are written? B/c this
> > symbol_request(s) look to me a bit ugly.
>
> It's a workaround for not having a hard dependency.  The HD-audio
> codec driver is generic, and we don't want to load the multiple WMI
> drivers always for using a Realtek codec.
>
> Ugly, yes, but simple enough.

Okay, thanks for elaboration.

-- 
With Best Regards,
Andy Shevchenko