linux-kernel - Re: [PATCH net-next v1 01/14] net: phy: nxp-c45-tja11xx: fix the PTP interrupt enablig/disabling

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Date:   Mon, 19 Jun 2023 11:42:28 +0300
From:   "Radu Pirea (OSS)" <radu-nicolae.pirea@....nxp.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        richardcochran@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, sebastian.tobuschat@....com,
        stable@...r.kernel.org
Subject: Re: [PATCH net-next v1 01/14] net: phy: nxp-c45-tja11xx: fix the PTP
 interrupt enablig/disabling

On 16.06.2023 23:36, Andrew Lunn wrote:
> On Fri, Jun 16, 2023 at 04:53:10PM +0300, Radu Pirea (NXP OSS) wrote:
>> .config_intr() handles only the link event interrupt and should
>> disable/enable the PTP interrupt also.
>>
>> It's safe to disable/enable the PTP irq even if the egress ts irq
>> is disabled. This interrupt, the PTP one, acts as a global switch for all
>> PTP irqs.
>>
>> Fixes: 514def5dd339 ("phy: nxp-c45-tja11xx: add timestamping support")
>> CC: stable@...r.kernel.org # 5.15+
>> Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@....nxp.com>
> 
> Please don't mix fixes and development work in one patchset. Please
> post this to applying to net, not net-next.

Ok. I will send it to net and apply your suggestions.

> 
>>   static int nxp_c45_config_intr(struct phy_device *phydev)
>>   {
>> -     if (phydev->interrupts == PHY_INTERRUPT_ENABLED)
>> +     /* The return value is ignored on purpose. It might be < 0.
>> +      * 0x807A register is not present on SJA1110 PHYs.
>> +      */
>> +     if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
>> +             phy_set_bits_mmd(phydev, MDIO_MMD_VEND1,
>> +                              VEND1_PORT_FUNC_IRQ_EN, PTP_IRQS);
>>                return phy_set_bits_mmd(phydev, MDIO_MMD_VEND1,
>>                                        VEND1_PHY_IRQ_EN, PHY_IRQ_LINK_EVENT);
> 
> phy_set_bits_mmd() will not return an error if the register does not
> exist. There is no such indication for MDIO. This is going to do a
> read/modify/write. That read might get 0xffff, or random junk. And
> then the write back will be successful. The only time
> phy_read()/phy_write return error is when there is a problem within
> the bus master, like its clock gets turned off and the transfer times
> out.
> 
> So it is good to document you are accessing a register which might not
> exist, but there is no need to ignore the return code.
> 
>         Andrew

-- 
Radu P.