linux-kernel - Re: [PATCH v2 2/2] usb: typec: Add support for Parade PS8830 Type-C Retimer

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Message-ID: <ZxdialY3h9YW2NdL@linaro.org>
Date: Tue, 22 Oct 2024 11:29:30 +0300
From: Abel Vesa <abel.vesa@...aro.org>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Rajendra Nayak <quic_rjendra@...cinc.com>,
	Sibi Sankar <quic_sibis@...cinc.com>,
	Johan Hovold <johan@...nel.org>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Trilok Soni <quic_tsoni@...cinc.com>, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/2] usb: typec: Add support for Parade PS8830 Type-C
 Retimer

On 24-10-22 09:41:42, Christophe JAILLET wrote:
> Le 04/10/2024 à 15:57, Abel Vesa a écrit :
> > The Parade PS8830 is a Type-C muti-protocol retimer controlled over I2C.
> > It provides both altmode and orientation handling.
> > 
> > Add a driver with support for the following modes:
> >   - DP 4lanes
> >   - DP 2lanes + USB3
> >   - USB3
> > 
> > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> > ---
> 
> Hi,
> 
> > +static int ps8830_retimer_probe(struct i2c_client *client)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct typec_switch_desc sw_desc = { };
> > +	struct typec_retimer_desc rtmr_desc = { };
> > +	struct ps8830_retimer *retimer;
> > +	int ret;
> > +
> > +	retimer = devm_kzalloc(dev, sizeof(*retimer), GFP_KERNEL);
> > +	if (!retimer)
> > +		return -ENOMEM;
> > +
> > +	retimer->client = client;
> > +
> > +	mutex_init(&retimer->lock);
> > +
> > +	retimer->regmap = devm_regmap_init_i2c(client, &ps8830_retimer_regmap);
> > +	if (IS_ERR(retimer->regmap)) {
> > +		dev_err(dev, "failed to allocate register map\n");
> > +		return PTR_ERR(retimer->regmap);
> > +	}
> > +
> > +	ret = ps8830_get_vregs(retimer);
> > +	if (ret)
> > +		return ret;
> > +
> > +	retimer->xo_clk = devm_clk_get(dev, "xo");
> > +	if (IS_ERR(retimer->xo_clk))
> > +		return dev_err_probe(dev, PTR_ERR(retimer->xo_clk),
> > +				     "failed to get xo clock\n");
> > +
> > +	retimer->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> > +	if (IS_ERR(retimer->reset_gpio))
> > +		return dev_err_probe(dev, PTR_ERR(retimer->reset_gpio),
> > +				     "failed to get reset gpio\n");
> > +
> > +	retimer->typec_switch = fwnode_typec_switch_get(dev->fwnode);
> > +	if (IS_ERR(retimer->typec_switch)) {
> > +		dev_err(dev, "failed to acquire orientation-switch\n");
> > +		return PTR_ERR(retimer->typec_switch);
> > +	}
> > +
> > +	retimer->typec_mux = fwnode_typec_mux_get(dev->fwnode);
> > +	if (IS_ERR(retimer->typec_mux)) {
> > +		dev_err(dev, "failed to acquire mode-mux\n");
> > +		goto err_switch_put;
> > +	}
> > +
> > +	sw_desc.drvdata = retimer;
> > +	sw_desc.fwnode = dev_fwnode(dev);
> > +	sw_desc.set = ps8830_sw_set;
> > +
> > +	ret = drm_aux_bridge_register(dev);
> > +	if (ret)
> > +		goto err_mux_put;
> > +
> > +	retimer->sw = typec_switch_register(dev, &sw_desc);
> > +	if (IS_ERR(retimer->sw)) {
> > +		dev_err(dev, "failed to register typec switch\n");
> > +		goto err_aux_bridge_unregister;
> > +	}
> > +
> > +	rtmr_desc.drvdata = retimer;
> > +	rtmr_desc.fwnode = dev_fwnode(dev);
> > +	rtmr_desc.set = ps8830_retimer_set;
> > +
> > +	retimer->retimer = typec_retimer_register(dev, &rtmr_desc);
> > +	if (IS_ERR(retimer->retimer)) {
> > +		dev_err(dev, "failed to register typec retimer\n");
> > +		goto err_switch_unregister;
> > +	}
> > +
> > +	ret = clk_prepare_enable(retimer->xo_clk);
> > +	if (ret) {
> > +		dev_err(dev, "failed to enable XO: %d\n", ret);
> > +		goto err_retimer_unregister;
> > +	}
> > +
> > +	ret = ps8830_enable_vregs(retimer);
> > +	if (ret)
> > +		goto err_clk_disable;
> > +
> > +	/* delay needed as per datasheet */
> > +	usleep_range(4000, 14000);
> > +
> > +	gpiod_set_value(retimer->reset_gpio, 1);
> > +
> > +	return 0;
> > +
> > +err_clk_disable:
> > +	clk_disable_unprepare(retimer->xo_clk);
> > +
> > +err_retimer_unregister:
> > +	typec_retimer_unregister(retimer->retimer);
> > +
> > +err_switch_unregister:
> > +	typec_switch_unregister(retimer->sw);
> > +
> > +err_aux_bridge_unregister:
> > +	gpiod_set_value(retimer->reset_gpio, 0);
> 
> Is this called useful here?
> gpiod_set_value(, 1) has not been called yet.
> 
> It made sense to have something like that in v1, but it looks strange in v2.
> 

The devm_gpiod_get() flag sets it to HIGH.

Anyway, this will be reworked in v3 as the reset gpio is active low.

> CJ
> 
> > +	clk_disable_unprepare(retimer->xo_clk);
> > +
> > +err_mux_put:
> > +	typec_mux_put(retimer->typec_mux);
> > +
> > +err_switch_put:
> > +	typec_switch_put(retimer->typec_switch);
> > +
> > +	return ret;
> > +}
> 
> ...