Hello Bryan, On 15.09.23 11:52, Bryan O'Donoghue wrote: > On 15/09/2023 07:50, 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@xxxxxxxxxxxxxx> >> --- >> drivers/usb/typec/tipd/core.c | 21 ++++++++++++++++++++- >> 1 file changed, 20 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/typec/tipd/core.c >> b/drivers/usb/typec/tipd/core.c >> index 37b56ce75f39..550f5913e985 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); >> + > > This looks a bit odd to me, shouldn't you drive reset to zero ? > > if (tps->reset) { > gpiod_set_value_cansleep(tps->reset, 0); > msleep(SETUP_MS); > } > The reset line is driven to zero by means fo the GPIOD_OUT_LOW flag, so there is no need to set it explicitly again. > also wouldn't it make sense to functionally decompose that and reuse in > probe() and tps6598x_resume() ? > > tps6598x_reset() { > if (tps->reset) { > gpiod_set_value_cansleep(tps->reset, 0); > msleep(SETUP_MS); > } > } > I can move the reset action to a separate function as you proposed, but then I suppose it would make sense to use the same function for both reset levels. Maybe something like: tps6598x_reset(bool level) { if (tps->reset) { gpiod_set_value_cansleep(tps->reset, level); if (!level) msleep(SETUP_MS); } } > --- > bod Thanks for your feedback. Best regards, Javier Carrasco
