linux-kernel - Re: [PATCH 1/2] i2c: imx-lpi2c: add bus recovery feature

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Message-ID: <20230613231948.bsxuou4nnwbg2ui5@intel.intel>
Date:   Wed, 14 Jun 2023 01:19:48 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     carlos.song@....com
Cc:     aisheng.dong@....com, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        Anson.Huang@....com, xiaoning.wang@....com, haibo.chen@....com,
        linux-imx@....com, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i2c: imx-lpi2c: add bus recovery feature

Hi,

On Mon, May 29, 2023 at 03:43:01PM +0800, carlos.song@....com wrote:
> From: Clark Wang <xiaoning.wang@....com>
> 
> Add bus recovery feature for LPI2C.
> Need add gpio pinctrl, scl-gpios and sda-gpios configuration in dts.

please update the commit message according to the dts changes, as
well.

[...]

> +static void lpi2c_imx_prepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct lpi2c_imx_struct *lpi2c_imx;
> +
> +	lpi2c_imx = container_of(adap, struct lpi2c_imx_struct, adapter);
> +
> +	pinctrl_select_state(lpi2c_imx->pinctrl, lpi2c_imx->pinctrl_pins_gpio);
> +}
> +
> +static void lpi2c_imx_unprepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct lpi2c_imx_struct *lpi2c_imx;
> +
> +	lpi2c_imx = container_of(adap, struct lpi2c_imx_struct, adapter);
> +
> +	pinctrl_select_state(lpi2c_imx->pinctrl, lpi2c_imx->pinctrl_pins_default);
> +}
> +
> +/*
> + * We switch SCL and SDA to their GPIO function and do some bitbanging
> + * for bus recovery. These alternative pinmux settings can be
> + * described in the device tree by a separate pinctrl state "gpio". If

is this still true?

> + * this is missing this is not a big problem, the only implication is
> + * that we can't do bus recovery.
> + */
> +static int lpi2c_imx_init_recovery_info(struct lpi2c_imx_struct *lpi2c_imx,
> +		struct platform_device *pdev)
> +{
> +	struct i2c_bus_recovery_info *rinfo = &lpi2c_imx->rinfo;
> +
> +	lpi2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (!lpi2c_imx->pinctrl || IS_ERR(lpi2c_imx->pinctrl)) {
> +		dev_info(&pdev->dev, "can't get pinctrl, bus recovery not supported\n");
> +		return PTR_ERR(lpi2c_imx->pinctrl);
> +	}
> +
> +	lpi2c_imx->pinctrl_pins_default = pinctrl_lookup_state(lpi2c_imx->pinctrl,
> +			PINCTRL_STATE_DEFAULT);
> +	lpi2c_imx->pinctrl_pins_gpio = pinctrl_lookup_state(lpi2c_imx->pinctrl,
> +			"gpio");
> +	rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
> +	rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
> +
> +	if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER ||
> +	    PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER) {
> +		return -EPROBE_DEFER;
> +	} else if (IS_ERR(rinfo->sda_gpiod) ||
> +		   IS_ERR(rinfo->scl_gpiod) ||
> +		   IS_ERR(lpi2c_imx->pinctrl_pins_default) ||
> +		   IS_ERR(lpi2c_imx->pinctrl_pins_gpio)) {
> +		dev_dbg(&pdev->dev, "recovery information incomplete\n");
> +		return 0;
> +	}

Why not use these assignement from the default
i2c_init_recovery()? Is there anything you are doing I am not
seeing?

> +
> +	dev_info(&pdev->dev, "using scl%s for recovery\n",
> +		 rinfo->sda_gpiod ? ",sda" : "");

is there any case when sda_gpiod is NULL?

> +
> +	rinfo->prepare_recovery = lpi2c_imx_prepare_recovery;
> +	rinfo->unprepare_recovery = lpi2c_imx_unprepare_recovery;
> +	rinfo->recover_bus = i2c_generic_scl_recovery;
> +	lpi2c_imx->adapter.bus_recovery_info = rinfo;

do you need also the set_scl() function? It should be mandatory.

> +
> +	return 0;
> +}

Besides, this is a copy/paste from i2c-imx.c, any chance to put
the two things together?

Andi