linux-kernel - Re: [PATCH v5 3/3] I2C: mediatek: Add driver for MediaTek MT8173 I2C controller

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Message-ID: <20150323073905.GF9742@pengutronix.de>
Date:	Mon, 23 Mar 2015 08:39:05 +0100
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Eddie Huang <eddie.huang@...iatek.com>
Cc:	Wolfram Sang <wsa@...-dreams.de>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Mark Rutland <mark.rutland@....com>,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	David Box <david.e.box@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Jean Delvare <jdelvare@...e.de>,
	Xudong Chen <xudong.chen@...iatek.com>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Arnd Bergmann <arnd@...db.de>,
	Liguo Zhang <liguo.zhang@...iatek.com>,
	Wei Yan <sledge.yanwei@...wei.com>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	Neelesh Gupta <neelegup@...ux.vnet.ibm.com>,
	devicetree@...r.kernel.org, Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Beniamino Galvani <b.galvani@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	linux-mediatek@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, srv_heupstream@...iatek.com,
	Anders Berg <anders.berg@...gotech.com>,
	Jim Cromie <jim.cromie@...il.com>,
	Simon Glass <sjg@...omium.org>,
	Max Schwarz <max.schwarz@...ine.de>,
	Doug Anderson <dianders@...omium.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	Kumar Gala <galak@...eaurora.org>
Subject: Re: [PATCH v5 3/3] I2C: mediatek: Add driver for MediaTek MT8173 I2C
 controller

On Sat, Mar 21, 2015 at 02:05:22PM +0800, Eddie Huang wrote:
> Add mediatek MT8173 I2C controller driver. Compare to I2C controller
> of earlier mediatek SoC, MT8173 fix write-then-read limitation, and
> also increase message size to 64kb.
> 

[...]

> +static const struct i2c_adapter_quirks mt8173_i2c_quirks = {
> +	.max_num_msgs = MAX_MSG_NUM_MT8173,
> +	.max_write_len = MAX_DMA_TRANS_SIZE_MT8173,
> +	.max_read_len = MAX_DMA_TRANS_SIZE_MT8173,
> +	.max_comb_1st_msg_len = MAX_DMA_TRANS_SIZE_MT8173,
> +	.max_comb_2nd_msg_len = MAX_WRRD_TRANS_SIZE_MT8173,
> +};
> +
>  static int mtk_i2c_probe(struct platform_device *pdev)
>  {
>  	int ret = 0;
> @@ -587,7 +626,8 @@ static int mtk_i2c_probe(struct platform_device *pdev)
>  		return -EINVAL;
>  
>  	i2c->platform_compat = mtk_get_device_prop(pdev);
> -	if (i2c->have_pmic && (i2c->platform_compat & COMPAT_MT6577))
> +	if (i2c->have_pmic && (i2c->platform_compat &
> +			(COMPAT_MT6577 | COMPAT_MT8173)))
>  		return -EINVAL;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -613,7 +653,10 @@ static int mtk_i2c_probe(struct platform_device *pdev)
>  	i2c->adap.dev.parent = &pdev->dev;
>  	i2c->adap.owner = THIS_MODULE;
>  	i2c->adap.algo = &mtk_i2c_algorithm;
> -	i2c->adap.quirks = &mt6577_i2c_quirks;
> +	if (i2c->platform_compat & COMPAT_MT8173)
> +		i2c->adap.quirks = &mt8173_i2c_quirks;
> +	else
> +		i2c->adap.quirks = &mt6577_i2c_quirks;

Instead of putting an integer into struct of_device_id you should
introduce a

struct mtk_i2c_data {
	struct i2c_adapter_quirks quirks;
	int compat;
	/* Additional SoC specific data */
};

and put a pointer to this directly into the of_device_id. This way you
need less casting and can put newly discovered differences diretly into
some data struct and don't have to introduce if(socxy) ... else ...
everytime.

Sascha

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