linux-kernel - Re: [PATCH net v2] net: ti: icssg-prueth: Fix emac link speed handling

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Message-ID: <40a7cc6c-363e-4516-847d-9ac6164203ef@ti.com>
Date: Tue, 5 Aug 2025 11:19:57 +0530
From: MD Danish Anwar <danishanwar@...com>
To: Andrew Lunn <andrew@...n.ch>
CC: Andrew Lunn <andrew+netdev@...n.ch>,
        "David S. Miller"
	<davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Meghana Malladi
	<m-malladi@...com>,
        Himanshu Mittal <h-mittal1@...com>,
        <linux-arm-kernel@...ts.infradead.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <srk@...com>,
        Vignesh Raghavendra
	<vigneshr@...com>,
        Roger Quadros <rogerq@...nel.org>
Subject: Re: [PATCH net v2] net: ti: icssg-prueth: Fix emac link speed
 handling

Hi Andrew,

On 04/08/25 10:19 pm, Andrew Lunn wrote:
> On Fri, Aug 01, 2025 at 05:49:48PM +0530, MD Danish Anwar wrote:
>> When link settings are changed emac->speed is populated by
>> emac_adjust_link(). The link speed and other settings are then written into
>> the DRAM. However if both ports are brought down after this and brought up
>> again or if the operating mode is changed and a firmware reload is needed,
>> the DRAM is cleared by icssg_config(). As a result the link settings are
>> lost.
>>
>> Fix this by calling emac_adjust_link() after icssg_config(). This re
>> populates the settings in the DRAM after a new firmware load.
>>
>> Fixes: 9facce84f406 ("net: ti: icssg-prueth: Fix firmware load sequence.")
>> Signed-off-by: MD Danish Anwar <danishanwar@...com>
>> ---
>> v1 - v2: Added phydev lock before calling emac_adjust_link() as suggested
>> by Andrew Lunn <andrew@...n.ch>
>> v1 https://lore.kernel.org/all/20250731120812.1606839-1-danishanwar@ti.com/
>>
>>  drivers/net/ethernet/ti/icssg/icssg_prueth.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
>> index 2b973d6e2341..58aec94b7771 100644
>> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
>> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
>> @@ -50,6 +50,8 @@
>>  /* CTRLMMR_ICSSG_RGMII_CTRL register bits */
>>  #define ICSSG_CTRL_RGMII_ID_MODE                BIT(24)
>>  
>> +static void emac_adjust_link(struct net_device *ndev);
>> +
>>  static int emac_get_tx_ts(struct prueth_emac *emac,
>>  			  struct emac_tx_ts_response *rsp)
>>  {
>> @@ -229,6 +231,12 @@ static int prueth_emac_common_start(struct prueth *prueth)
>>  		ret = icssg_config(prueth, emac, slice);
>>  		if (ret)
>>  			goto disable_class;
>> +
>> +		if (emac->ndev->phydev) {
>> +			mutex_lock(&emac->ndev->phydev->lock);
>> +			emac_adjust_link(emac->ndev);
>> +			mutex_unlock(&emac->ndev->phydev->lock);
>> +		}
> 
> What about the else case? The link settings are lost, and the MAC does
> not work?
> 

Actually this if else is not needed at all. If phydev == NULL, the
driver would have already returned -ENODEV in emac_phy_connect() and the
device's probe would have failed.

If we have reached this point that means phydev is not null and there is
no need for this check.

I will drop this if check and send a v3.

> 	Andrew

-- 
Thanks and Regards,
Danish