netdev - Re: [PATCH net-next 2/2] net: pse-pd: tps23881: support reset-gpios

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Message-ID: <ZsQ2fuqWkMYwq_kh@pengutronix.de>
Date: Tue, 20 Aug 2024 08:23:58 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Kyle Swenson <kyle.swenson@....tech>
Cc: "kory.maincent@...tlin.com" <kory.maincent@...tlin.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	"robh@...nel.org" <robh@...nel.org>,
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>,
	"thomas.petazzoni@...tlin.com" <thomas.petazzoni@...tlin.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH net-next 2/2] net: pse-pd: tps23881: support reset-gpios

Hi Kyle,

thank you for you patch.

On Mon, Aug 19, 2024 at 07:02:14PM +0000, Kyle Swenson wrote:
> The TPS23880/1 has an active-low reset pin that some boards connect to
> the SoC to control when the TPS23880 is pulled out of reset.
> 
> Add support for this via a reset-gpios property in the DTS.
> 
> Signed-off-by: Kyle Swenson <kyle.swenson@....tech>
> ---
>  drivers/net/pse-pd/tps23881.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
> index 2ea75686a319..837e1a2119ee 100644
> --- a/drivers/net/pse-pd/tps23881.c
> +++ b/drivers/net/pse-pd/tps23881.c
> @@ -6,16 +6,16 @@
>   */
>  
>  #include <linux/bitfield.h>
>  #include <linux/delay.h>
>  #include <linux/firmware.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
>  #include <linux/pse-pd/pse.h>
> -

No need to remove space here.

>  #define TPS23881_MAX_CHANS 8
>  
>  #define TPS23881_REG_PW_STATUS	0x10
>  #define TPS23881_REG_OP_MODE	0x12
>  #define TPS23881_OP_MODE_SEMIAUTO	0xaaaa
> @@ -735,10 +735,11 @@ static int tps23881_flash_sram_fw(struct i2c_client *client)
>  
>  static int tps23881_i2c_probe(struct i2c_client *client)
>  {
>  	struct device *dev = &client->dev;
>  	struct tps23881_priv *priv;
> +	struct gpio_desc *reset;
>  	int ret;
>  	u8 val;
>  
>  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
>  		dev_err(dev, "i2c check functionality failed\n");
> @@ -747,10 +748,20 @@ static int tps23881_i2c_probe(struct i2c_client *client)
>  
>  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>  	if (!priv)
>  		return -ENOMEM;
>  
> +	reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(reset))
> +		return dev_err_probe(&client->dev, PTR_ERR(reset), "Failed to get reset GPIO\n");
> +
> +	if (reset) {
> +		usleep_range(1000, 10000);
> +		gpiod_set_value_cansleep(reset, 0); /* De-assert reset */
> +		usleep_range(1000, 10000);

According to the datasheet, page 13:
https://www.ti.com/lit/ds/symlink/tps23880.pdf

Minimal reset time is 5 microseconds and the delay after power on reset should
be at least 20 milliseconds. Both sleep values should be corrected.

Regards,
Oleksij
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