linux-kernel - Re: [PATCH v3] net: mdiobus: Add a function to deassert reset

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Message-ID: <KL1PR01MB54483E67F238214C1E087246E6779@KL1PR01MB5448.apcprd01.prod.exchangelabs.com>
Date:   Wed, 10 May 2023 18:30:04 +0800
From:   Yan Wang <rk.code@...look.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     andrew@...n.ch, hkallweit1@...il.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux@...linux.org.uk
Subject: Re: [PATCH v3] net: mdiobus: Add a function to deassert reset



On 5/10/2023 6:22 PM, Simon Horman wrote:
> On Wed, May 10, 2023 at 04:15:22PM +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.
>>
>> I found that the subsequent drive registers the reset pin into the
>> structure of the sub-device to prevent conflicts, so release the
>> reset pin.
>>
>> Signed-off-by: Yan Wang <rk.code@...look.com>
>> ---
>> v3:
>>    - fixed commit message
>> v2: https://lore.kernel.org/all/KL1PR01MB54482416A8BE0D80EA27223CE6779@KL1PR01MB5448.apcprd01.prod.exchangelabs.com/
>>    - fixed commit message
>>    - Using gpiod_ replace gpio_
>> v1: https://lore.kernel.org/all/KL1PR01MB5448631F2D6F71021602117FE6769@KL1PR01MB5448.apcprd01.prod.exchangelabs.com/
>>    - Incorrect description of commit message.
>>    - The gpio-api too old
>> ---
>>   drivers/net/mdio/fwnode_mdio.c | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
>> index 1183ef5e203e..6695848b8ef2 100644
>> --- a/drivers/net/mdio/fwnode_mdio.c
>> +++ b/drivers/net/mdio/fwnode_mdio.c
>> @@ -57,6 +57,20 @@ 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;
>> +
>> +	reset = fwnode_gpiod_get_index(fwnode, "reset", 0, GPIOD_OUT_HIGH, NULL);
> Hi Yan,
>
> As this calls fwnode_gpiod_get_index()
> do you need to include linux/gpio/consumer.h ?
Ok, I found and fixing
>> +	if (IS_ERR(reset) && PTR_ERR(reset) != -EPROBE_DEFER)
>> +		return;
>> +
>> +	usleep_range(100, 200);
>> +	gpiod_set_value_cansleep(reset, 0);
>> +	/*Release the reset pin,it needs to be registered with the PHY.*/
>> +	gpiod_put(reset);
>> +}
>> +
> ...