linux-kernel - Re: [PATCH v2] drivers/media/dvb-frontends: Implement probe/remove for stv6110x

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Date:   Wed, 29 May 2019 11:45:33 -0700
From:   Joe Perches <joe@...ches.com>
To:     Tobias Klausmann <tobias.johannes.klausmann@....thm.de>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        mchehab@...nel.org, sean@...s.org
Subject: Re: [PATCH v2] drivers/media/dvb-frontends: Implement probe/remove
 for stv6110x

On Wed, 2019-05-29 at 18:56 +0200, Tobias Klausmann wrote:
> Refactor out the common parts of stv6110x_probe() and stv6110x_attach()
> into separate functions.
> 
> This provides the needed functionality to use dvb_module_probe() instead
> of dvb_attach()!
> 
> v2:
> - Impovments based on comments by Sean Young
> - Fix checkpatch.pl --strict errors

trivia:

> diff --git a/drivers/media/dvb-frontends/stv6110x.c b/drivers/media/dvb-frontends/stv6110x.c
[]
> @@ -333,6 +333,41 @@ static void stv6110x_release(struct dvb_frontend *fe)
>  	kfree(stv6110x);
>  }
>  
> +void st6110x_init_regs(struct stv6110x_state *stv6110x)
> +{
> +	u8 default_regs[] = {0x07, 0x11, 0xdc, 0x85, 0x17, 0x01, 0xe6, 0x1e};

static const u8...

> +
> +	memcpy(stv6110x->regs, default_regs, 8);

	memcpy(stv6110x->regs, default_regs, ARRAY_SIZE(default_regs));

> +}
> +
> +void stv6110x_setup_divider(struct stv6110x_state *stv6110x)
> +{
> +	switch (stv6110x->config->clk_div) {
> +	default:
> +	case 1:
> +		STV6110x_SETFIELD(stv6110x->regs[STV6110x_CTRL2],
> +				  CTRL2_CO_DIV,
> +				  0);
> +		break;
> +	case 2:
> +		STV6110x_SETFIELD(stv6110x->regs[STV6110x_CTRL2],
> +				  CTRL2_CO_DIV,
> +				  1);
> +		break;
> +	case 4:
> +		STV6110x_SETFIELD(stv6110x->regs[STV6110x_CTRL2],
> +				  CTRL2_CO_DIV,
> +				  2);
> +		break;
> +	case 8:
> +	case 0:
> +		STV6110x_SETFIELD(stv6110x->regs[STV6110x_CTRL2],
> +				  CTRL2_CO_DIV,
> +				  3);
> +		break;
> +	}
> +}

Probably more sensible (and smaller object code) written using
an automatic like:

{
	int div;

	switch (stv6110x->config->clk_div) {
	case 8:
		div = 3;
		break;
	case 4:
		div = 2;
		break;
	case 2:
		div = 1;
		break;
	case 1:
	default:
		div = 0;
		break;
	}
	STV6110x_SETFIELD(stv6110x->regs[STV6110x_CTRL2], CTRL2_CO_DIV, div);
}

> diff --git a/drivers/media/dvb-frontends/stv6110x_priv.h b/drivers/media/dvb-frontends/stv6110x_priv.h
[]
> @@ -54,11 +54,12 @@
>  #define REFCLOCK_MHz				(stv6110x->config->refclk / 1000000)
>  
>  struct stv6110x_state {
> +	struct dvb_frontend		*frontend;
>  	struct i2c_adapter		*i2c;
>  	const struct stv6110x_config	*config;
>  	u8				regs[8];

Perhaps this 8 should be a define?