[PATCH 06/14] net: phy: ksz90x1: Handle ksz9131 LED errata

[Marek Vasut]

On 10/28/24 9:47 AM, Paul Barker wrote:
> On 27/10/2024 16:18, Marek Vasut wrote:
>> On 10/24/24 5:24 PM, Paul Barker wrote:
>>> Micrel KSZ9131 PHY LED behavior is not correct when configured in
>>> Individual Mode, LED1 (Activity LED) is in the ON state when there is
>>> no-link.
>>>
>>> Workaround this by setting bit 9 of register 0x1e after verifying that
>>> the LED configuration is Individual Mode.
>>>
>>> This issue is described in KSZ9131RNX Silicon Errata DS80000693B [*]
>>> and according to that it will not be corrected in a future silicon
>>> revision.
>>>
>>> [*] https://ww1.microchip.com/downloads/en/DeviceDoc/KSZ9131RNX-Silicon-Errata-and-Data-Sheet-Clarification-80000863B.pdf
>>>
>>> Based on commit 0316c7e66bbd in the Linux kernel.
>>>
>>> Signed-off-by: Paul Barker <paul.barker.ct at bp.renesas.com>
>>> ---
>>>    drivers/net/phy/micrel_ksz90x1.c | 24 ++++++++++++++++++++++++
>>>    1 file changed, 24 insertions(+)
>>>
>>> diff --git a/drivers/net/phy/micrel_ksz90x1.c b/drivers/net/phy/micrel_ksz90x1.c
>>> index c48ae6e88f30..4f99b115a3c7 100644
>>> --- a/drivers/net/phy/micrel_ksz90x1.c
>>> +++ b/drivers/net/phy/micrel_ksz90x1.c
>>> @@ -436,6 +436,26 @@ static int ksz9131_config_rgmii_delay(struct phy_device *phydev)
>>>    	return ret;
>>>    }
>>>    
>>> +/* Silicon Errata DS80000693B
>>> + *
>>> + * When LEDs are configured in Individual Mode, LED1 is ON in a no-link
>>> + * condition. Workaround is to set register 0x1e, bit 9, this way LED1 behaves
>>> + * according to the datasheet (off if there is no link).
>>> + */
>>> +static int ksz9131_led_errata(struct phy_device *phydev)
>>> +{
>>> +	int reg;
>>> +
>>> +	reg = phy_read_mmd(phydev, KSZ9131RN_MMD_COMMON_CTRL_REG, 0);
>>> +	if (reg < 0)
>>> +		return reg;
>>> +
>>> +	if (!(reg & BIT(4)))
>> It would be good to have symbolic names for these BIT()s , please add
>> some #define ... macros .
> 
> I can add symbolic names for the values used above
> (KSZ9131RN_COMMON_CTRL=0 and KSZ9131RN_COMMON_CTRL_LED_MODE=BIT(4)).
> 
> The arguments used in the following phy_set_bits() call are a bit
> trickier - all the errata document says is "Register 0x1E (30d), bit 9
> must be set to 1". The Linux kernel commit adding this workaround
> doesn't have any symbolic names either.
Maybe also send a kernel patch ?