Re: [PATCH net-next v4 3/3] net: ethernet: oa_tc6: add reset-gpios support

[Parthiban Veerasooran <parthiban.veerasooran@microchip.com>]

Hi Alessandro,

On 19/09/26 4:44 am, Alessandro Zini wrote:
> 
>   #include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>   #include <linux/iopoll.h>
>   #include <linux/interrupt.h>
>   #include <linux/mdio.h>
> @@ -88,6 +90,7 @@ struct oa_tc6 {
>          bool disable_traffic;
>          bool prot_ctrl;
>          enum oa_tc6_quirk_flag quirk_flags;
> +       struct gpio_desc *reset_gpio;
>   };
> 
>   enum oa_tc6_header_type {
> @@ -1504,6 +1507,22 @@ struct oa_tc6 *oa_tc6_init(struct spi_device *spi, struct net_device *netdev,
>          if (!tc6->spi_data_rx_buf)
>                  return ERR_PTR(-ENOMEM);
> 
> +       tc6->reset_gpio = devm_gpiod_get_optional(&spi->dev, "reset",
> +                                                 GPIOD_OUT_HIGH);
> +       if (IS_ERR(tc6->reset_gpio))
> +               return ERR_PTR(dev_err_probe(&spi->dev,
> +                                            PTR_ERR(tc6->reset_gpio),
> +                                            "failed to get reset gpio\n"));
> +
> +       if (tc6->reset_gpio) {
> +               /* Keep the reset asserted for 10 us and then allow 1 ms of
> +                * settle time for the crystal oscillator startup.
> +                */
> +               fsleep(10);
> +               gpiod_set_value_cansleep(tc6->reset_gpio, 0);
> +               fsleep(1000);
> +       }
> +

How do we ensure that the reset has completed before proceeding? Should 
we check for a reset-complete status indication instead of relying only 
on fixed delays?

Also, do we still need oa_tc6_sw_reset_macphy() when reset_gpio is 
implemented? My understanding is that the software reset path is mainly 
needed for MAC-PHYs that do not expose a reset GPIO. In that case, it 
may be cleaner to prefer the GPIO reset when available and fall back to 
the software reset otherwise, rather than always performing both resets.

Best regards,
Parthiban V>          /* Check the PROTE bit status so that we can reset 
the device */
>          ret = oa_tc6_check_ctrl_protection(tc6);
>          if (ret) {
> --
> 2.55.0