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SubjectRe: [PATCH v4] net: mdiobus: Add a function to deassert reset
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On 5/11/2023 8:40 PM, Simon Horman wrote:
> On Thu, May 11, 2023 at 02:59:09PM +0800, Yan Wang wrote:
>> It is possible to mount multiple sub-devices on the mido bus.
>> The hardware power-on does not necessarily reset these devices.
>> The device may be in an uncertain state, causing the device's ID
>> to not be scanned.
>>
>> So,before adding a reset to the scan, make sure the device is in
>> normal working mode.
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Link: https://lore.kernel.org/oe-kbuild-all/202305101702.4xW6vT72-lkp@intel.com/
>> Signed-off-by: Yan Wang <rk.code@outlook.com>
> ...
>
>> diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
>> index 1183ef5e203e..9d7df6393059 100644
>> --- a/drivers/net/mdio/fwnode_mdio.c
>> +++ b/drivers/net/mdio/fwnode_mdio.c
>> @@ -11,6 +11,7 @@
>> #include <linux/of.h>
>> #include <linux/phy.h>
>> #include <linux/pse-pd/pse.h>
>> +#include <linux/gpio/consumer.h>
>>
>> MODULE_AUTHOR("Calvin Johnson <calvin.johnson@oss.nxp.com>");
>> MODULE_LICENSE("GPL");
>> @@ -57,6 +58,35 @@ fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
>> return register_mii_timestamper(arg.np, arg.args[0]);
>> }
>>
>> +static void fwnode_mdiobus_pre_enable_phy(struct fwnode_handle *fwnode)
>> +{
>> + struct gpio_desc *reset;
>> + unsigned int reset_assert_delay;
>> + unsigned int reset_deassert_delay;
> nit: Please arrange local variables for networking code in reverse xmas
> tree order - longest line to shortest.
>
>> +
>> + reset = fwnode_gpiod_get_index(fwnode, "reset", 0, GPIOD_OUT_LOW, NULL);
>> + if (IS_ERR(reset)) {
>> + if (PTR_ERR(reset) == -EPROBE_DEFER)
>> + pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
>> + to_of_node(fwnode), __func__);
>> + else
>> + pr_err("%pOFn: %s: Can't get reset line property\n",
>> + to_of_node(fwnode), __func__);
>> +
>> + return;
>> + }
>> + fwnode_property_read_u32(fwnode, "reset-assert-us",
>> + &reset_assert_delay);
>> + fwnode_property_read_u32(fwnode, "reset-deassert-us",
>> + &reset_deassert_delay);
> Does the return value of fwnode_property_read_u32() need to be
> checked for errors?
>
>> + gpiod_set_value_cansleep(reset, 1);
>> + fsleep(reset_assert_delay);
>> + gpiod_set_value_cansleep(reset, 0);
>> + fsleep(reset_deassert_delay);
>> + /*Release phy's reset line, mdiobus_register_gpiod() need to request it*/
> nit:
>
> /* Release phy's reset line, mdiobus_register_gpiod() needs to
> * request it.
> */

Thank you for your suggestion.

Best Regards
>> + gpiod_put(reset);
>> +}
>> +
>> int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
>> struct phy_device *phy,
>> struct fwnode_handle *child, u32 addr)
>> @@ -119,6 +149,8 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
>> u32 phy_id;
>> int rc;
>>
>> + fwnode_mdiobus_pre_enable_phy(child);
>> +
>> psec = fwnode_find_pse_control(child);
>> if (IS_ERR(psec))
>> return PTR_ERR(psec);
>> --
>> 2.17.1
>>
>>

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