linux-kernel - Re: [PATCH] media: dummy_dvb_fe: register adapter/frontend

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Message-ID: <20191201085602.7212436b@kernel.org>
Date:   Sun, 1 Dec 2019 08:56:02 +0100
From:   Mauro Carvalho Chehab <mchehab@...nel.org>
To:     "Daniel W. S. Almeida" <dwlsalmeida@...il.com>
Cc:     gregkh@...uxfoundation.org, rfontana@...hat.com,
        kstewart@...uxfoundation.org, tglx@...utronix.de,
        skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: dummy_dvb_fe: register adapter/frontend

Em Tue, 26 Nov 2019 12:31:57 -0300
"Daniel W. S. Almeida" <dwlsalmeida@...il.com> escreveu:

> From: "Daniel W. S. Almeida" <dwlsalmeida@...il.com>
> 
> Before using the DTV frontend core, a bridge driver should register the
> new frontend at the subsystem and unregister it at device detach / removal.

This patch is conceptually wrong. The dummy_dvb_fe is a frontend driver.

As such, it doesn't register itself as a bridge. What we need here is a
separate virtual DVB bridge driver with would register itself as a DVB
adapter and use the dummy_dvb_fe as its frontend.

Regards,
Mauro

> 
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@...il.com>
> ---
>  drivers/media/dvb-frontends/dvb_dummy_fe.c | 39 ++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/dvb-frontends/dvb_dummy_fe.c b/drivers/media/dvb-frontends/dvb_dummy_fe.c
> index 4db679cb70ad..1ccb58c67e8e 100644
> --- a/drivers/media/dvb-frontends/dvb_dummy_fe.c
> +++ b/drivers/media/dvb-frontends/dvb_dummy_fe.c
> @@ -13,12 +13,12 @@
>  #include <media/dvb_frontend.h>
>  #include "dvb_dummy_fe.h"
>  
> +DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
>  
>  struct dvb_dummy_fe_state {
>  	struct dvb_frontend frontend;
>  };
>  
> -
>  static int dvb_dummy_fe_read_status(struct dvb_frontend *fe,
>  				    enum fe_status *status)
>  {
> @@ -84,7 +84,36 @@ static int dvb_dummy_fe_sleep(struct dvb_frontend* fe)
>  
>  static int dvb_dummy_fe_init(struct dvb_frontend* fe)
>  {
> -	return 0;
> +	int result = 0;
> +	struct dvb_adapter *adapter = fe->dvb;
> +
> +	result = dvb_register_adapter(adapter,
> +				      KBUILD_MODNAME,
> +				      THIS_MODULE,
> +				      adapter->device,
> +				      adapter_nr);
> +
> +	if (!result) {
> +		pr_err("DVB_DUMMY_FE: Failed to register the adapter, errno:%d",
> +			result);
> +		goto err;
> +	}
> +
> +	result = dvb_register_frontend(adapter, fe);
> +	if (!result) {
> +		pr_err("DVB_DUMMY_FE: Failed to register the frontend, errno:%d",
> +			result);
> +		goto err;
> +	}
> +
> +	return result;
> +
> +err:
> +	dvb_unregister_adapter(adapter);
> +	dvb_unregister_frontend(fe);
> +	dvb_frontend_detach(fe);
> +	return result;
> +
>  }
>  
>  static int dvb_dummy_fe_set_tone(struct dvb_frontend *fe,
> @@ -102,6 +131,12 @@ static int dvb_dummy_fe_set_voltage(struct dvb_frontend *fe,
>  static void dvb_dummy_fe_release(struct dvb_frontend* fe)
>  {
>  	struct dvb_dummy_fe_state* state = fe->demodulator_priv;
> +	struct dvb_adapter *adapter = fe->dvb;
> +
> +	dvb_unregister_adapter(adapter);
> +	dvb_unregister_frontend(fe);
> +	dvb_frontend_detach(fe);
> +
>  	kfree(state);
>  }
>  



Cheers,
Mauro