linux-kernel - Re: [PATCH v2 1/2] usb: typec: tps6598x: add reset gpio support

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Message-ID: <ZQRayaqdtrqYl4AT@kuha.fi.intel.com>
Date:   Fri, 15 Sep 2023 16:23:21 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Javier Carrasco <javier.carrasco@...fvision.net>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 1/2] usb: typec: tps6598x: add reset gpio support

Hi,

On Fri, Sep 15, 2023 at 03:17:28PM +0200, Javier Carrasco wrote:
> On 15.09.23 14:57, Heikki Krogerus wrote:
> > On Fri, Sep 15, 2023 at 02:23:48PM +0200, Javier Carrasco wrote:
> >> The TPS6598x PD controller provides an active-high hardware reset input
> >> that reinitializes all device settings. If it is not grounded by
> >> design, the driver must be able to de-assert it in order to initialize
> >> the device.
> >>
> >> The PD controller is not ready for registration right after the reset
> >> de-assertion and a delay must be introduced in that case. According to
> >> TI, the delay can reach up to 1000 ms [1], which is in line with the
> >> experimental results obtained with a TPS65987D.
> >>
> >> Add a GPIO descriptor for the reset signal and basic reset management
> >> for initialization and suspend/resume.
> >>
> >> [1] https://e2e.ti.com/support/power-management-group/power-management/
> >> f/power-management-forum/1269856/tps65987d-tps65987d-reset-de-assert-
> >> to-normal-operation/4809389#4809389
> >>
> >> Signed-off-by: Javier Carrasco <javier.carrasco@...fvision.net>
> >> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> >> ---
> >>  drivers/usb/typec/tipd/core.c | 20 ++++++++++++++++++++
> >>  1 file changed, 20 insertions(+)
> >>
> >> diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
> >> index 37b56ce75f39..3068ef300073 100644
> >> --- a/drivers/usb/typec/tipd/core.c
> >> +++ b/drivers/usb/typec/tipd/core.c
> >> @@ -8,6 +8,7 @@
> >>  
> >>  #include <linux/i2c.h>
> >>  #include <linux/acpi.h>
> >> +#include <linux/gpio/consumer.h>
> >>  #include <linux/module.h>
> >>  #include <linux/of.h>
> >>  #include <linux/power_supply.h>
> >> @@ -43,6 +44,9 @@
> >>  /* TPS_REG_SYSTEM_CONF bits */
> >>  #define TPS_SYSCONF_PORTINFO(c)		((c) & 7)
> >>  
> >> +/* reset de-assertion to ready for operation */
> >> +#define SETUP_MS			1000
> >> +
> >>  enum {
> >>  	TPS_PORTINFO_SINK,
> >>  	TPS_PORTINFO_SINK_ACCESSORY,
> >> @@ -86,6 +90,7 @@ struct tps6598x {
> >>  	struct mutex lock; /* device lock */
> >>  	u8 i2c_protocol:1;
> >>  
> >> +	struct gpio_desc *reset;
> >>  	struct typec_port *port;
> >>  	struct typec_partner *partner;
> >>  	struct usb_pd_identity partner_identity;
> >> @@ -717,6 +722,13 @@ static int tps6598x_probe(struct i2c_client *client)
> >>  	mutex_init(&tps->lock);
> >>  	tps->dev = &client->dev;
> >>  
> >> +	tps->reset = devm_gpiod_get_optional(tps->dev, "reset", GPIOD_OUT_LOW);
> >> +	if (IS_ERR(tps->reset))
> >> +		return dev_err_probe(tps->dev, PTR_ERR(tps->reset),
> >> +				     "failed to get reset GPIO\n");
> >> +	if (tps->reset)
> >> +		msleep(SETUP_MS);
> >> +
> >>  	tps->regmap = devm_regmap_init_i2c(client, &tps6598x_regmap_config);
> >>  	if (IS_ERR(tps->regmap))
> >>  		return PTR_ERR(tps->regmap);
> >> @@ -892,6 +904,9 @@ static void tps6598x_remove(struct i2c_client *client)
> >>  	tps6598x_disconnect(tps, 0);
> >>  	typec_unregister_port(tps->port);
> >>  	usb_role_switch_put(tps->role_sw);
> >> +
> >> +	if (tps->reset)
> >> +		gpiod_set_value_cansleep(tps->reset, 1);
> > 
> > Do you need that "if (tps->reset)" in this case? That function is NULL safe,
> > right?
> > 
> The function makes use of the VALIDATE_DESC_VOID macro to make it NULL
> safe, but this macro also calls pr_warn if the descriptor is NULL and I
> do not want to add warnings for an optional property that did not exist
> before because it could be confusing. But if that is the desired
> behavior, I will remove the checks.

No, I don't want noise either.

> >>  }
> >>  
> >>  static int __maybe_unused tps6598x_suspend(struct device *dev)
> >> @@ -902,6 +917,8 @@ static int __maybe_unused tps6598x_suspend(struct device *dev)
> >>  	if (tps->wakeup) {
> >>  		disable_irq(client->irq);
> >>  		enable_irq_wake(client->irq);
> >> +	} else if (tps->reset) {
> >> +		gpiod_set_value_cansleep(tps->reset, 1);
> >>  	}
> >>  
> >>  	if (!client->irq)
> >> @@ -918,6 +935,9 @@ static int __maybe_unused tps6598x_resume(struct device *dev)
> >>  	if (tps->wakeup) {
> >>  		disable_irq_wake(client->irq);
> >>  		enable_irq(client->irq);
> >> +	} else if (tps->reset) {
> >> +		gpiod_set_value_cansleep(tps->reset, 0);
> >> +		msleep(SETUP_MS);
> >>  	}
> >>  
> >>  	if (!client->irq)
> >>
> >> -- 
> >> 2.39.2

thanks,

-- 
heikki