[PATCH] net: phy: at803x: disable delay only for RGMII mode

[PATCH] net: phy: at803x: disable delay only for RGMII mode

[Vinod Koul]

Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
can have delay in phy.

So disable the delay only for RGMII mode and disable for other modes

Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 drivers/net/phy/at803x.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 8ff12938ab47..7b54b54e3316 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
 	return phy_write(phydev, AT803X_DEBUG_DATA, val);
 }
 
+static inline int at803x_enable_rx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
+				     AT803X_DEBUG_RX_CLK_DLY_EN);
+}
+
+static inline int at803x_enable_tx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
+				     AT803X_DEBUG_TX_CLK_DLY_EN);
+}
+
 static inline int at803x_disable_rx_delay(struct phy_device *phydev)
 {
 	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
@@ -255,18 +267,25 @@ static int at803x_config_init(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
-	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
 		ret = at803x_disable_rx_delay(phydev);
 		if (ret < 0)
 			return ret;
+		ret = at803x_disable_tx_delay(phydev);
+		if (ret < 0)
+			return ret;
+	};
+
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+			phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
+		ret = at803x_enable_rx_delay(phydev);
+		if (ret < 0)
+			return ret;
 	}
 
-	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
-		ret = at803x_disable_tx_delay(phydev);
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+			phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
+		ret = at803x_enable_tx_delay(phydev);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.20.1

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Vinod,

On 12/02/2019 16.19, Vinod Koul wrote:
> Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
> should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
> can have delay in phy.
> 
> So disable the delay only for RGMII mode and disable for other modes
s/disable for other modes/enable for other modes

Works fine on am335x-evmsk:
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

and few comment

> Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
> Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>  drivers/net/phy/at803x.c | 33 ++++++++++++++++++++++++++-------
>  1 file changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index 8ff12938ab47..7b54b54e3316 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>  }
>  
> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> +}

static inline int at803x_select_rx_delay(struct phy_device *phydev,
					 bool enable)
{
}

> +
> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> +}

static inline int at803x_select_tx_delay(struct phy_device *phydev,
					 bool enable)
{
}

perhaps?

> +
>  static inline int at803x_disable_rx_delay(struct phy_device *phydev)
>  {
>  	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
> @@ -255,18 +267,25 @@ static int at803x_config_init(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
>  		ret = at803x_disable_rx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
> +		ret = at803x_disable_tx_delay(phydev);
> +		if (ret < 0)
> +			return ret;

is it a possibility to have PHY_INTERFACE_MODE_RGMII and other RGMII_ID
|| RGMII_TXID || RGMII_RXID set at the same time?

if not you can just return from here, no need to check for other RGMII
modes?

> +	};
> +
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> +		ret = at803x_enable_rx_delay(phydev);
> +		if (ret < 0)
> +			return ret;
>  	}
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> -		ret = at803x_disable_tx_delay(phydev);
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> +		ret = at803x_enable_tx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
>  	}
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Vinod,

On 12/02/2019 16.19, Vinod Koul wrote:
> Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
> should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
> can have delay in phy.
> 
> So disable the delay only for RGMII mode and disable for other modes
s/disable for other modes/enable for other modes

Works fine on am335x-evmsk:
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

and few comment

> Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
> Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>  drivers/net/phy/at803x.c | 33 ++++++++++++++++++++++++++-------
>  1 file changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index 8ff12938ab47..7b54b54e3316 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>  }
>  
> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> +}

static inline int at803x_select_rx_delay(struct phy_device *phydev,
					 bool enable)
{
}

> +
> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> +}

static inline int at803x_select_tx_delay(struct phy_device *phydev,
					 bool enable)
{
}

perhaps?

> +
>  static inline int at803x_disable_rx_delay(struct phy_device *phydev)
>  {
>  	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
> @@ -255,18 +267,25 @@ static int at803x_config_init(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
>  		ret = at803x_disable_rx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
> +		ret = at803x_disable_tx_delay(phydev);
> +		if (ret < 0)
> +			return ret;

is it a possibility to have PHY_INTERFACE_MODE_RGMII and other RGMII_ID
|| RGMII_TXID || RGMII_RXID set at the same time?

if not you can just return from here, no need to check for other RGMII
modes?

> +	};
> +
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> +		ret = at803x_enable_rx_delay(phydev);
> +		if (ret < 0)
> +			return ret;
>  	}
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> -		ret = at803x_disable_tx_delay(phydev);
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> +		ret = at803x_enable_tx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
>  	}
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Vinod Koul]

On 13-02-19, 09:02, Peter Ujfalusi wrote:
> Hi Vinod,
> 
> On 12/02/2019 16.19, Vinod Koul wrote:
> > Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
> > should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
> > can have delay in phy.
> > 
> > So disable the delay only for RGMII mode and disable for other modes
> s/disable for other modes/enable for other modes

oops

> 
> Works fine on am335x-evmsk:
> Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

Thanks for quick testing..

> 
> and few comment
> 
> > Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
> > Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> >  drivers/net/phy/at803x.c | 33 ++++++++++++++++++++++++++-------
> >  1 file changed, 26 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> > index 8ff12938ab47..7b54b54e3316 100644
> > --- a/drivers/net/phy/at803x.c
> > +++ b/drivers/net/phy/at803x.c
> > @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
> >  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
> >  }
> >  
> > +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> > +{
> > +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> > +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> > +}
> 
> static inline int at803x_select_rx_delay(struct phy_device *phydev,
> 					 bool enable)
> {
> }
> 
> > +
> > +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> > +{
> > +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> > +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> > +}
> 
> static inline int at803x_select_tx_delay(struct phy_device *phydev,
> 					 bool enable)
> {
> }
> 
> perhaps?

Given that we would again branch off on enable, I see this as no better
case so I will keep existing

> 
> > +
> >  static inline int at803x_disable_rx_delay(struct phy_device *phydev)
> >  {
> >  	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
> > @@ -255,18 +267,25 @@ static int at803x_config_init(struct phy_device *phydev)
> >  	if (ret < 0)
> >  		return ret;
> >  
> > -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> > -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> > -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> > +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> >  		ret = at803x_disable_rx_delay(phydev);
> >  		if (ret < 0)
> >  			return ret;
> > +		ret = at803x_disable_tx_delay(phydev);
> > +		if (ret < 0)
> > +			return ret;
> 
> is it a possibility to have PHY_INTERFACE_MODE_RGMII and other RGMII_ID
> || RGMII_TXID || RGMII_RXID set at the same time?

Nope that would not make sense

> if not you can just return from here, no need to check for other RGMII
> modes?

for RGMII yes indeed..

-- 
~Vinod

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

On Tue, Feb 12, 2019 at 07:49:22PM +0530, Vinod Koul wrote:
> Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
> should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
> can have delay in phy.
> 
> So disable the delay only for RGMII mode and disable for other modes
> 
> Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
> Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>  drivers/net/phy/at803x.c | 33 ++++++++++++++++++++++++++-------
>  1 file changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index 8ff12938ab47..7b54b54e3316 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>  }
>  
> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> +}
> +
> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> +}
> +
>  static inline int at803x_disable_rx_delay(struct phy_device *phydev)
>  {
>  	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
> @@ -255,18 +267,25 @@ static int at803x_config_init(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
>  		ret = at803x_disable_rx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
> +		ret = at803x_disable_tx_delay(phydev);
> +		if (ret < 0)
> +			return ret;
> +	};
> +
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> +		ret = at803x_enable_rx_delay(phydev);
> +		if (ret < 0)
> +			return ret;
>  	}
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> -		ret = at803x_disable_tx_delay(phydev);
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +			phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> +		ret = at803x_enable_tx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
>  	}

So we have these modes:

PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled

What I don't like with this patch, is that if we specify phy-mode
PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
but RX delay will not be explicitly set.

Thus it will use the default value of the PHY, and for this PHY
both TX and RX delays are enabled by default.

This means that someone specifying PHY_INTERFACE_MODE_RGMII_TXID
will actually be getting PHY_INTERFACE_MODE_RGMII_ID.


Marc's patch:
https://www.spinics.net/lists/netdev/msg445053.html

does explicitly either enable or disable each delay
(so it does not depend on default values).


However, Marc's patch was never merged, because someone reported
a regression on am335x-evm.


On Vinod's V1 submission Andrew replied that if this change
breaks some existing DT (because that DT specifies a phy-mode
that does not match with reality), then we should fix so that
DT specifies the correct phy-mode:
https://www.spinics.net/lists/netdev/msg542638.html

IMHO, this makes most sense, since if a DT specifies an
incorrect phy-mode, then that is what the user should get.


Kind regards,
Niklas

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Andrew Lunn]

> So we have these modes:
> 
> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
> 
> What I don't like with this patch, is that if we specify phy-mode
> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
> but RX delay will not be explicitly set.

That is not the behaviour we want. It is best to assume the device is
in a random state, and correctly enable/disable all delays as
requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
used.

     Andrew

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Marc Gonzalez]

On 13/02/2019 14:29, Andrew Lunn wrote:

>> So we have these modes:
>>
>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>
>> What I don't like with this patch, is that if we specify phy-mode
>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>> but RX delay will not be explicitly set.
> 
> That is not the behaviour we want. It is best to assume the device is
> in a random state, and correctly enable/disable all delays as
> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> used.

That's what my patch did:
https://www.spinics.net/lists/netdev/msg445053.html

But see Florian's remarks:
https://www.spinics.net/lists/netdev/msg445133.html

Regards.

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Marc Gonzalez]

On 13/02/2019 14:29, Andrew Lunn wrote:

>> So we have these modes:
>>
>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>
>> What I don't like with this patch, is that if we specify phy-mode
>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>> but RX delay will not be explicitly set.
> 
> That is not the behaviour we want. It is best to assume the device is
> in a random state, and correctly enable/disable all delays as
> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> used.

That's what my patch did:
https://www.spinics.net/lists/netdev/msg445053.html

But see Florian's remarks:
https://www.spinics.net/lists/netdev/msg445133.html

Regards.

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

[-- Attachment #1: Type: text/plain, Size: 1762 bytes --]

On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
> On 13/02/2019 14:29, Andrew Lunn wrote:
> 
> >> So we have these modes:
> >>
> >> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
> >> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
> >> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
> >> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
> >>
> >> What I don't like with this patch, is that if we specify phy-mode
> >> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
> >> but RX delay will not be explicitly set.
> > 
> > That is not the behaviour we want. It is best to assume the device is
> > in a random state, and correctly enable/disable all delays as
> > requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> > used.
> 
> That's what my patch did:
> https://www.spinics.net/lists/netdev/msg445053.html
> 
> But see Florian's remarks:
> https://www.spinics.net/lists/netdev/msg445133.html

Hello Marc,

I saw that comment from Florian. However that was way back in 2017.
Maybe the phy-modes were not as well defined back then?

Andrew recently suggested to fix the driver so that it conforms with the
phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
and thus relied upon the broken behavior of the PHY driver:
https://www.spinics.net/lists/netdev/msg445133.html


So, I've rebased your old patch, see attachment.
I suggest that Peter test it on am335x-evm.

am335x-evm appears to rely on the current broken behavior of the PHY
driver, so we will probably need to fix the am335x-evm according to this:
https://www.spinics.net/lists/netdev/msg445117.html
and merge that as well.


Andrew, Florian, do you both agree?


Kind regards,
Niklas

[-- Attachment #2: 0001-net-phy-at803x-Fix-RGMII-RX-and-TX-clock-delays-setu.patch --]
[-- Type: text/plain, Size: 2911 bytes --]

>From 7f19f32d3074c9990e46349b76ae13dc9c1133d6 Mon Sep 17 00:00:00 2001
From: Marc Gonzalez <marc.w.gonzalez@free.fr>
Date: Wed, 13 Feb 2019 18:29:02 +0100
Subject: [PATCH] net: phy: at803x: Fix RGMII RX and TX clock delays setup

The current code supports enabling RGMII RX and TX clock delays.
The unstated assumption is that these settings are disabled by
default at reset, which is not the case.

RX clock delay is enabled at reset. And TX clock delay "survives"
across SW resets. Thus, if the bootloader enables TX clock delay,
it will remain enabled at reset in Linux.

Provide disable functions to configure the RGMII clock delays
exactly as specified in the fwspec.

Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
---
 drivers/net/phy/at803x.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 90dc62c15fc5..700c1e4d34ad 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -103,12 +103,24 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
 	return phy_write(phydev, AT803X_DEBUG_DATA, val);
 }
 
+static inline int at803x_enable_rx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
+				     AT803X_DEBUG_RX_CLK_DLY_EN);
+}
+
 static inline int at803x_disable_rx_delay(struct phy_device *phydev)
 {
 	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
 				     AT803X_DEBUG_RX_CLK_DLY_EN, 0);
 }
 
+static inline int at803x_enable_tx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
+				     AT803X_DEBUG_TX_CLK_DLY_EN);
+}
+
 static inline int at803x_disable_tx_delay(struct phy_device *phydev)
 {
 	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5,
@@ -242,20 +254,22 @@ static int at803x_config_init(struct phy_device *phydev)
 		return ret;
 
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
+		ret = at803x_enable_rx_delay(phydev);
+	else
 		ret = at803x_disable_rx_delay(phydev);
-		if (ret < 0)
-			return ret;
-	}
+
+	if (ret < 0)
+		return ret;
 
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
+		ret = at803x_enable_tx_delay(phydev);
+	else
 		ret = at803x_disable_tx_delay(phydev);
-		if (ret < 0)
-			return ret;
-	}
+
+	if (ret < 0)
+		return ret;
 
 	return 0;
 }
-- 
2.20.1

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

[-- Attachment #1: Type: text/plain, Size: 1762 bytes --]

On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
> On 13/02/2019 14:29, Andrew Lunn wrote:
> 
> >> So we have these modes:
> >>
> >> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
> >> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
> >> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
> >> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
> >>
> >> What I don't like with this patch, is that if we specify phy-mode
> >> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
> >> but RX delay will not be explicitly set.
> > 
> > That is not the behaviour we want. It is best to assume the device is
> > in a random state, and correctly enable/disable all delays as
> > requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> > used.
> 
> That's what my patch did:
> https://www.spinics.net/lists/netdev/msg445053.html
> 
> But see Florian's remarks:
> https://www.spinics.net/lists/netdev/msg445133.html

Hello Marc,

I saw that comment from Florian. However that was way back in 2017.
Maybe the phy-modes were not as well defined back then?

Andrew recently suggested to fix the driver so that it conforms with the
phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
and thus relied upon the broken behavior of the PHY driver:
https://www.spinics.net/lists/netdev/msg445133.html


So, I've rebased your old patch, see attachment.
I suggest that Peter test it on am335x-evm.

am335x-evm appears to rely on the current broken behavior of the PHY
driver, so we will probably need to fix the am335x-evm according to this:
https://www.spinics.net/lists/netdev/msg445117.html
and merge that as well.


Andrew, Florian, do you both agree?


Kind regards,
Niklas

[-- Attachment #2: 0001-net-phy-at803x-Fix-RGMII-RX-and-TX-clock-delays-setu.patch --]
[-- Type: text/plain, Size: 2910 bytes --]

From 7f19f32d3074c9990e46349b76ae13dc9c1133d6 Mon Sep 17 00:00:00 2001
From: Marc Gonzalez <marc.w.gonzalez@free.fr>
Date: Wed, 13 Feb 2019 18:29:02 +0100
Subject: [PATCH] net: phy: at803x: Fix RGMII RX and TX clock delays setup

The current code supports enabling RGMII RX and TX clock delays.
The unstated assumption is that these settings are disabled by
default at reset, which is not the case.

RX clock delay is enabled at reset. And TX clock delay "survives"
across SW resets. Thus, if the bootloader enables TX clock delay,
it will remain enabled at reset in Linux.

Provide disable functions to configure the RGMII clock delays
exactly as specified in the fwspec.

Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
---
 drivers/net/phy/at803x.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 90dc62c15fc5..700c1e4d34ad 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -103,12 +103,24 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
 	return phy_write(phydev, AT803X_DEBUG_DATA, val);
 }
 
+static inline int at803x_enable_rx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
+				     AT803X_DEBUG_RX_CLK_DLY_EN);
+}
+
 static inline int at803x_disable_rx_delay(struct phy_device *phydev)
 {
 	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
 				     AT803X_DEBUG_RX_CLK_DLY_EN, 0);
 }
 
+static inline int at803x_enable_tx_delay(struct phy_device *phydev)
+{
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
+				     AT803X_DEBUG_TX_CLK_DLY_EN);
+}
+
 static inline int at803x_disable_tx_delay(struct phy_device *phydev)
 {
 	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5,
@@ -242,20 +254,22 @@ static int at803x_config_init(struct phy_device *phydev)
 		return ret;
 
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
+		ret = at803x_enable_rx_delay(phydev);
+	else
 		ret = at803x_disable_rx_delay(phydev);
-		if (ret < 0)
-			return ret;
-	}
+
+	if (ret < 0)
+		return ret;
 
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
+		ret = at803x_enable_tx_delay(phydev);
+	else
 		ret = at803x_disable_tx_delay(phydev);
-		if (ret < 0)
-			return ret;
-	}
+
+	if (ret < 0)
+		return ret;
 
 	return 0;
 }
-- 
2.20.1

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Florian Fainelli]

On 2/13/19 9:40 AM, Niklas Cassel wrote:
> On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
>> On 13/02/2019 14:29, Andrew Lunn wrote:
>>
>>>> So we have these modes:
>>>>
>>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>>>
>>>> What I don't like with this patch, is that if we specify phy-mode
>>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>>>> but RX delay will not be explicitly set.
>>>
>>> That is not the behaviour we want. It is best to assume the device is
>>> in a random state, and correctly enable/disable all delays as
>>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
>>> used.
>>
>> That's what my patch did:
>> https://www.spinics.net/lists/netdev/msg445053.html
>>
>> But see Florian's remarks:
>> https://www.spinics.net/lists/netdev/msg445133.html
> 
> Hello Marc,
> 
> I saw that comment from Florian. However that was way back in 2017.
> Maybe the phy-modes were not as well defined back then?

The definition of the 'phy-mode' was clarified to be understood from the
perspective of the PHY device (hence the name) after we had several
fruitful exchanges with Marc (at least from my perspective), but since
the definition was not clear before, there is a high chance of finding
DTS/DTBs out there with the 'phy-mode' property understood from the
MAC's perspective, which would now be wrong.


> 
> Andrew recently suggested to fix the driver so that it conforms with the
> phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> and thus relied upon the broken behavior of the PHY driver:
> https://www.spinics.net/lists/netdev/msg445133.html
> 
> 
> So, I've rebased your old patch, see attachment.
> I suggest that Peter test it on am335x-evm.
> 
> am335x-evm appears to rely on the current broken behavior of the PHY
> driver, so we will probably need to fix the am335x-evm according to this:
> https://www.spinics.net/lists/netdev/msg445117.html
> and merge that as well.
> 
> 
> Andrew, Florian, do you both agree?

In my reply to Marc, there was a concern that while am335x-evm was
identified and reported to be broken after fixing the PHY driver, there
could be platforms out there that we have little to no visibility that
would most likely be equally broken. That concern still exists, and I
don't think there is anything we can do to even assess the size of the
problem unless we attempt to fix it, so maybe we should attempt to fix that.

There was a suggestion to Marc that one way to possibly "ignore" an
incorrectly broken 'phy-mode' property would be to allow specifying
rx/tx delay properties such that if the driver obtained its
phy_interface_t, yet still parsed rx/tx delays, the rx/tx delays would
take precedence, and we could possibly derive some sort of a "more
correct" phy_interface_t that we could assign back to phydev->interface
and issue a warning about that.

Another possible way to resolve that could be to introduce a 'mac-mode'
property, which must be strictly compatible with specifying a 'phy-mode'
property. For instance:

- MAC specifies mac-mode = 'rgmii-id', then the PHY must have phy-mode =
'rmgii' since the MAC is taking of inserting both RX and TX delays,
reverse also applies

- MAC specifies mac-mode = 'rgmii-txid', then the PHY must have phy-mode
= 'rgmii-rxid' because the MAC adds the TX delay, but the PHY should
insert the delay on the RX lines, reverse also applies

Because there is usually (not always, DSA is an exception) a 1:1 mapping
between MAC and PHY devices we could look up the 'mac-mode' property in
the MAC in the PHY library code and make sure that we have a compatible
matrix and if we do not, maybe pass something like PHY_INTERFACE_MODE_NA
such that the driver retains its settings.

Maybe another way to approach this is if we assume that the PHY comes up
configured correctly by the boot loader, or upon power on reset, we add
some PHY driver methods that allow us to determine the RGMII mode in
which a PHY is and that tells us whether we are compatible with the
MAC's phy_interface_t upon connection. We check both at connect() time
and if something does not look right, we flip the meaning of
phy_interface_t.

None of those solutions are entirely fool proof, but at least we might
be able to detect incorrect combinations, yet still make them work by
reversing the meaning of the 'phy-mode' property given information at hand.

Let me know if none of that makes sense and this just looks like yet
another brain dump.

Wonderful RGMII...
-- 
Florian

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

On Wed, Feb 13, 2019 at 09:59:43AM -0800, Florian Fainelli wrote:
> On 2/13/19 9:40 AM, Niklas Cassel wrote:
> > On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
> >> On 13/02/2019 14:29, Andrew Lunn wrote:
> >>
> >>>> So we have these modes:
> >>>>
> >>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
> >>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
> >>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
> >>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
> >>>>
> >>>> What I don't like with this patch, is that if we specify phy-mode
> >>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
> >>>> but RX delay will not be explicitly set.
> >>>
> >>> That is not the behaviour we want. It is best to assume the device is
> >>> in a random state, and correctly enable/disable all delays as
> >>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> >>> used.
> >>
> >> That's what my patch did:
> >> https://www.spinics.net/lists/netdev/msg445053.html
> >>
> >> But see Florian's remarks:
> >> https://www.spinics.net/lists/netdev/msg445133.html
> > 
> > Hello Marc,
> > 
> > I saw that comment from Florian. However that was way back in 2017.
> > Maybe the phy-modes were not as well defined back then?
> 
> The definition of the 'phy-mode' was clarified to be understood from the
> perspective of the PHY device (hence the name) after we had several
> fruitful exchanges with Marc (at least from my perspective), but since
> the definition was not clear before, there is a high chance of finding
> DTS/DTBs out there with the 'phy-mode' property understood from the
> MAC's perspective, which would now be wrong.

Hello Florian,


We have a specification:
Documentation/devicetree/bindings/net/ethernet.txt

And several implementations: the PHY drivers.

Either we decide that all PHY drivers have to follow
the specification for "phy-mode" in
Documentation/devicetree/bindings/net/ethernet.txt
or we decide that they don't.

If we decide that all PHY drivers have to follow the specification,
then we can fix the PHY drivers that currently do not follow the
specification.

If we decide that all PHY drivers do not have to follow the spec,
then the "phy-mode" property is basically useless, and then we should
introduce a new device tree property, e.g. "phy-mode2", that is
guaranteed to respect the definitons in
Documentation/devicetree/bindings/net/ethernet.txt

> 
> 
> > 
> > Andrew recently suggested to fix the driver so that it conforms with the
> > phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> > and thus relied upon the broken behavior of the PHY driver:
> > https://www.spinics.net/lists/netdev/msg445133.html
> > 
> > 
> > So, I've rebased your old patch, see attachment.
> > I suggest that Peter test it on am335x-evm.
> > 
> > am335x-evm appears to rely on the current broken behavior of the PHY
> > driver, so we will probably need to fix the am335x-evm according to this:
> > https://www.spinics.net/lists/netdev/msg445117.html
> > and merge that as well.
> > 
> > 
> > Andrew, Florian, do you both agree?
> 
> In my reply to Marc, there was a concern that while am335x-evm was
> identified and reported to be broken after fixing the PHY driver, there
> could be platforms out there that we have little to no visibility that
> would most likely be equally broken. That concern still exists, and I
> don't think there is anything we can do to even assess the size of the
> problem unless we attempt to fix it, so maybe we should attempt to fix that.
> 
> There was a suggestion to Marc that one way to possibly "ignore" an
> incorrectly broken 'phy-mode' property would be to allow specifying
> rx/tx delay properties such that if the driver obtained its
> phy_interface_t, yet still parsed rx/tx delays, the rx/tx delays would
> take precedence, and we could possibly derive some sort of a "more
> correct" phy_interface_t that we could assign back to phydev->interface
> and issue a warning about that.

You mean to add new device tree properties to
Documentation/devicetree/bindings/net/ethernet.txt

- phy-id-tx: "true" if PHY should add internal delay on TX lines;
             "false" or not specified if PHY should not add internal
	     delay on TX lines. This property overrides any delay
	     requested by "phy-mode".
- phy-id-rx: "true" if PHY should add internal delay on RX lines;
             "false" or not specified if PHY should not add internal
	     delay on RX lines. This property overrides any delay
	     requested by "phy-mode".

Perhaps something like that?

Personally, I prefer making "phy-mode" strict,
but whatever you guys decide:
- making "phy-mode" strict
- introducing a "phy-mode2"
- introducing "phy-id-tx/phy-id-rx"
- introducing "mac-mode"
- some other solution

It is probably wise to introduce helper functions in phy.h
 phy_wants_id_rx()
 phy_wants_id_tx()
so that PHY drivers can simply use e.g.:

if (phy_wants_id_rx(phydev))
	at803x_enable_rx_delay(phydev);
else
	at803x_disable_rx_delay(phydev);

if (phy_wants_id_tx(phydev))
	at803x_enable_tx_delay(phydev);
else
	at803x_disable_tx_delay(phydev);

> 
> Another possible way to resolve that could be to introduce a 'mac-mode'
> property, which must be strictly compatible with specifying a 'phy-mode'
> property. For instance:
> 
> - MAC specifies mac-mode = 'rgmii-id', then the PHY must have phy-mode =
> 'rmgii' since the MAC is taking of inserting both RX and TX delays,
> reverse also applies
> 
> - MAC specifies mac-mode = 'rgmii-txid', then the PHY must have phy-mode
> = 'rgmii-rxid' because the MAC adds the TX delay, but the PHY should
> insert the delay on the RX lines, reverse also applies
> 
> Because there is usually (not always, DSA is an exception) a 1:1 mapping
> between MAC and PHY devices we could look up the 'mac-mode' property in
> the MAC in the PHY library code and make sure that we have a compatible
> matrix and if we do not, maybe pass something like PHY_INTERFACE_MODE_NA
> such that the driver retains its settings.

Is there any advantage of creating a "mac-mode" over creating a
"phy-mode2" ?


Kind regards,
Niklas

> 
> Maybe another way to approach this is if we assume that the PHY comes up
> configured correctly by the boot loader, or upon power on reset, we add
> some PHY driver methods that allow us to determine the RGMII mode in
> which a PHY is and that tells us whether we are compatible with the
> MAC's phy_interface_t upon connection. We check both at connect() time
> and if something does not look right, we flip the meaning of
> phy_interface_t.
> 
> None of those solutions are entirely fool proof, but at least we might
> be able to detect incorrect combinations, yet still make them work by
> reversing the meaning of the 'phy-mode' property given information at hand.
> 
> Let me know if none of that makes sense and this just looks like yet
> another brain dump.
> 
> Wonderful RGMII...
> -- 
> Florian

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Florian Fainelli]

On 2/13/19 12:07 PM, Niklas Cassel wrote:
> On Wed, Feb 13, 2019 at 09:59:43AM -0800, Florian Fainelli wrote:
>> On 2/13/19 9:40 AM, Niklas Cassel wrote:
>>> On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
>>>> On 13/02/2019 14:29, Andrew Lunn wrote:
>>>>
>>>>>> So we have these modes:
>>>>>>
>>>>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>>>>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>>>>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>>>>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>>>>>
>>>>>> What I don't like with this patch, is that if we specify phy-mode
>>>>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>>>>>> but RX delay will not be explicitly set.
>>>>>
>>>>> That is not the behaviour we want. It is best to assume the device is
>>>>> in a random state, and correctly enable/disable all delays as
>>>>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
>>>>> used.
>>>>
>>>> That's what my patch did:
>>>> https://www.spinics.net/lists/netdev/msg445053.html
>>>>
>>>> But see Florian's remarks:
>>>> https://www.spinics.net/lists/netdev/msg445133.html
>>>
>>> Hello Marc,
>>>
>>> I saw that comment from Florian. However that was way back in 2017.
>>> Maybe the phy-modes were not as well defined back then?
>>
>> The definition of the 'phy-mode' was clarified to be understood from the
>> perspective of the PHY device (hence the name) after we had several
>> fruitful exchanges with Marc (at least from my perspective), but since
>> the definition was not clear before, there is a high chance of finding
>> DTS/DTBs out there with the 'phy-mode' property understood from the
>> MAC's perspective, which would now be wrong.
> 
> Hello Florian,
> 
> 
> We have a specification:
> Documentation/devicetree/bindings/net/ethernet.txt
> 
> And several implementations: the PHY drivers.
> 
> Either we decide that all PHY drivers have to follow
> the specification for "phy-mode" in
> Documentation/devicetree/bindings/net/ethernet.txt
> or we decide that they don't.
> 
> If we decide that all PHY drivers have to follow the specification,
> then we can fix the PHY drivers that currently do not follow the
> specification.
> 
> If we decide that all PHY drivers do not have to follow the spec,
> then the "phy-mode" property is basically useless, and then we should
> introduce a new device tree property, e.g. "phy-mode2", that is
> guaranteed to respect the definitons in
> Documentation/devicetree/bindings/net/ethernet.txt

If the specification had been clear from day one, then we would not be
in the situation we are in today, so in that case it is not as simple
as: a) deprecating an existing property that was misused because the
spec was not well enough defined and b) go and fix all drivers. The
amount of breakage that can be introduced is just immense, and quite
frankly, for absolutely no good reason.

It's all well and good to introduce a 'phy-mode2' but let's think about
the future:

- what is depreciation path for 'phy-mode'/'phy-connection-type' looking
like then?
- do we have the manpower to review every new binding, DTS submission
that gets included in Linux, FreeBSD, Zephyr, for correctness?

> 
>>
>>
>>>
>>> Andrew recently suggested to fix the driver so that it conforms with the
>>> phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
>>> and thus relied upon the broken behavior of the PHY driver:
>>> https://www.spinics.net/lists/netdev/msg445133.html
>>>
>>>
>>> So, I've rebased your old patch, see attachment.
>>> I suggest that Peter test it on am335x-evm.
>>>
>>> am335x-evm appears to rely on the current broken behavior of the PHY
>>> driver, so we will probably need to fix the am335x-evm according to this:
>>> https://www.spinics.net/lists/netdev/msg445117.html
>>> and merge that as well.
>>>
>>>
>>> Andrew, Florian, do you both agree?
>>
>> In my reply to Marc, there was a concern that while am335x-evm was
>> identified and reported to be broken after fixing the PHY driver, there
>> could be platforms out there that we have little to no visibility that
>> would most likely be equally broken. That concern still exists, and I
>> don't think there is anything we can do to even assess the size of the
>> problem unless we attempt to fix it, so maybe we should attempt to fix that.
>>
>> There was a suggestion to Marc that one way to possibly "ignore" an
>> incorrectly broken 'phy-mode' property would be to allow specifying
>> rx/tx delay properties such that if the driver obtained its
>> phy_interface_t, yet still parsed rx/tx delays, the rx/tx delays would
>> take precedence, and we could possibly derive some sort of a "more
>> correct" phy_interface_t that we could assign back to phydev->interface
>> and issue a warning about that.
> 
> You mean to add new device tree properties to
> Documentation/devicetree/bindings/net/ethernet.txt
> 
> - phy-id-tx: "true" if PHY should add internal delay on TX lines;
>              "false" or not specified if PHY should not add internal
> 	     delay on TX lines. This property overrides any delay
> 	     requested by "phy-mode".
> - phy-id-rx: "true" if PHY should add internal delay on RX lines;
>              "false" or not specified if PHY should not add internal
> 	     delay on RX lines. This property overrides any delay
> 	     requested by "phy-mode".
> 
> Perhaps something like that?

Not quite booleans, actual delay values, e.g.:

tx-delay-ps = <2000>
rx-delay-ps = <2000>

this is something that exists already:

Documentation/devicetree/bindings/net/apm-xgene-enet.txt
Documentation/devicetree/bindings/net/cavium-pip.txt
Documentation/devicetree/bindings/net/dwmac-sun8i.txt

because conceptually, telling the PHY driver that a TX or RX delay is
simply not enough, sometimes the standard 2ns (90 degree shift at
125Mhz) is not good enough and gets you out of spec because of some
board design.

> 
> Personally, I prefer making "phy-mode" strict,
> but whatever you guys decide:
> - making "phy-mode" strict
> - introducing a "phy-mode2"
> - introducing "phy-id-tx/phy-id-rx"
> - introducing "mac-mode"
> - some other solution
> 
> It is probably wise to introduce helper functions in phy.h
>  phy_wants_id_rx()
>  phy_wants_id_tx()
> so that PHY drivers can simply use e.g.:
> 
> if (phy_wants_id_rx(phydev))
> 	at803x_enable_rx_delay(phydev);
> else
> 	at803x_disable_rx_delay(phydev);
> 
> if (phy_wants_id_tx(phydev))
> 	at803x_enable_tx_delay(phydev);
> else
> 	at803x_disable_tx_delay(phydev);

Yes, that I think is pretty much orthogonal to the end solution we
decide to choose, having a way to tell what the PHY is currently
configured, or capable of supporting is step 1 in trying to find a
compatibility solution.

> 
>>
>> Another possible way to resolve that could be to introduce a 'mac-mode'
>> property, which must be strictly compatible with specifying a 'phy-mode'
>> property. For instance:
>>
>> - MAC specifies mac-mode = 'rgmii-id', then the PHY must have phy-mode =
>> 'rmgii' since the MAC is taking of inserting both RX and TX delays,
>> reverse also applies
>>
>> - MAC specifies mac-mode = 'rgmii-txid', then the PHY must have phy-mode
>> = 'rgmii-rxid' because the MAC adds the TX delay, but the PHY should
>> insert the delay on the RX lines, reverse also applies
>>
>> Because there is usually (not always, DSA is an exception) a 1:1 mapping
>> between MAC and PHY devices we could look up the 'mac-mode' property in
>> the MAC in the PHY library code and make sure that we have a compatible
>> matrix and if we do not, maybe pass something like PHY_INTERFACE_MODE_NA
>> such that the driver retains its settings.
> 
> Is there any advantage of creating a "mac-mode" over creating a
> "phy-mode2" ?
> 
> 
> Kind regards,
> Niklas
> 
>>
>> Maybe another way to approach this is if we assume that the PHY comes up
>> configured correctly by the boot loader, or upon power on reset, we add
>> some PHY driver methods that allow us to determine the RGMII mode in
>> which a PHY is and that tells us whether we are compatible with the
>> MAC's phy_interface_t upon connection. We check both at connect() time
>> and if something does not look right, we flip the meaning of
>> phy_interface_t.
>>
>> None of those solutions are entirely fool proof, but at least we might
>> be able to detect incorrect combinations, yet still make them work by
>> reversing the meaning of the 'phy-mode' property given information at hand.
>>
>> Let me know if none of that makes sense and this just looks like yet
>> another brain dump.
>>
>> Wonderful RGMII...
>> -- 
>> Florian


-- 
Florian

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Niklas,

On 13/02/2019 19.40, Niklas Cassel wrote:
> On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
>> On 13/02/2019 14:29, Andrew Lunn wrote:
>>
>>>> So we have these modes:
>>>>
>>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>>>
>>>> What I don't like with this patch, is that if we specify phy-mode
>>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>>>> but RX delay will not be explicitly set.
>>>
>>> That is not the behaviour we want. It is best to assume the device is
>>> in a random state, and correctly enable/disable all delays as
>>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
>>> used.
>>
>> That's what my patch did:
>> https://www.spinics.net/lists/netdev/msg445053.html
>>
>> But see Florian's remarks:
>> https://www.spinics.net/lists/netdev/msg445133.html
> 
> Hello Marc,
> 
> I saw that comment from Florian. However that was way back in 2017.
> Maybe the phy-modes were not as well defined back then?
> 
> Andrew recently suggested to fix the driver so that it conforms with the
> phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> and thus relied upon the broken behavior of the PHY driver:
> https://www.spinics.net/lists/netdev/msg445133.html
> 
> 
> So, I've rebased your old patch, see attachment.
> I suggest that Peter test it on am335x-evm.

with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
is working.
I don't have am335x-evm to test, but it has the same PHY as evmsk.

> am335x-evm appears to rely on the current broken behavior of the PHY
> driver, so we will probably need to fix the am335x-evm according to this:
> https://www.spinics.net/lists/netdev/msg445117.html
> and merge that as well.
> 
> 
> Andrew, Florian, do you both agree?
> 
> 
> Kind regards,
> Niklas
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Niklas,

On 13/02/2019 19.40, Niklas Cassel wrote:
> On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
>> On 13/02/2019 14:29, Andrew Lunn wrote:
>>
>>>> So we have these modes:
>>>>
>>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>>>
>>>> What I don't like with this patch, is that if we specify phy-mode
>>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>>>> but RX delay will not be explicitly set.
>>>
>>> That is not the behaviour we want. It is best to assume the device is
>>> in a random state, and correctly enable/disable all delays as
>>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
>>> used.
>>
>> That's what my patch did:
>> https://www.spinics.net/lists/netdev/msg445053.html
>>
>> But see Florian's remarks:
>> https://www.spinics.net/lists/netdev/msg445133.html
> 
> Hello Marc,
> 
> I saw that comment from Florian. However that was way back in 2017.
> Maybe the phy-modes were not as well defined back then?
> 
> Andrew recently suggested to fix the driver so that it conforms with the
> phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> and thus relied upon the broken behavior of the PHY driver:
> https://www.spinics.net/lists/netdev/msg445133.html
> 
> 
> So, I've rebased your old patch, see attachment.
> I suggest that Peter test it on am335x-evm.

with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
is working.
I don't have am335x-evm to test, but it has the same PHY as evmsk.

> am335x-evm appears to rely on the current broken behavior of the PHY
> driver, so we will probably need to fix the am335x-evm according to this:
> https://www.spinics.net/lists/netdev/msg445117.html
> and merge that as well.
> 
> 
> Andrew, Florian, do you both agree?
> 
> 
> Kind regards,
> Niklas
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

On Thu, Feb 14, 2019 at 12:49:36PM +0200, Peter Ujfalusi wrote:
> Hi Niklas,
> 
> On 13/02/2019 19.40, Niklas Cassel wrote:
> > On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
> >> On 13/02/2019 14:29, Andrew Lunn wrote:
> >>
> >>>> So we have these modes:
> >>>>
> >>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
> >>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
> >>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
> >>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
> >>>>
> >>>> What I don't like with this patch, is that if we specify phy-mode
> >>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
> >>>> but RX delay will not be explicitly set.
> >>>
> >>> That is not the behaviour we want. It is best to assume the device is
> >>> in a random state, and correctly enable/disable all delays as
> >>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
> >>> used.
> >>
> >> That's what my patch did:
> >> https://www.spinics.net/lists/netdev/msg445053.html
> >>
> >> But see Florian's remarks:
> >> https://www.spinics.net/lists/netdev/msg445133.html
> > 
> > Hello Marc,
> > 
> > I saw that comment from Florian. However that was way back in 2017.
> > Maybe the phy-modes were not as well defined back then?
> > 
> > Andrew recently suggested to fix the driver so that it conforms with the
> > phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> > and thus relied upon the broken behavior of the PHY driver:
> > https://www.spinics.net/lists/netdev/msg445133.html
> > 
> > 
> > So, I've rebased your old patch, see attachment.
> > I suggest that Peter test it on am335x-evm.
> 
> with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
> is working.
> I don't have am335x-evm to test, but it has the same PHY as evmsk.
> 

Florian's concern was that this PHY driver looked at "phy-mode" from the
perspective of the MAC rather than the PHY.
However, if s/rgmii-txid/rgmii-id is the correct fix for am335x-evm,
then this means that this PHY driver was just broken.

If the driver had misinterpreted the perspective, then the correct
fix for am335x-evm would have been s/rgmii-txid/rgmii-rxid.

So considering that this driver seems to be really broken
(rather then just inverted perspective),
perhaps we can merge the patch I attached in my previous email after all?
(Together with a s/rgmii-txid/rgmii-id in the am335x-evmsk.dts.)


Kind regards,
Niklas

> > am335x-evm appears to rely on the current broken behavior of the PHY
> > driver, so we will probably need to fix the am335x-evm according to this:
> > https://www.spinics.net/lists/netdev/msg445117.html
> > and merge that as well.
> > 
> > 
> > Andrew, Florian, do you both agree?
> > 
> > 
> > Kind regards,
> > Niklas
> > 
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Niklas,

On 14/02/2019 14.39, Niklas Cassel wrote:
>>> So, I've rebased your old patch, see attachment.
>>> I suggest that Peter test it on am335x-evm.
>>
>> with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
>> is working.
>> I don't have am335x-evm to test, but it has the same PHY as evmsk.
>>
> 
> Florian's concern was that this PHY driver looked at "phy-mode" from the
> perspective of the MAC rather than the PHY.
> However, if s/rgmii-txid/rgmii-id is the correct fix for am335x-evm,
> then this means that this PHY driver was just broken.
> 
> If the driver had misinterpreted the perspective, then the correct
> fix for am335x-evm would have been s/rgmii-txid/rgmii-rxid.

Not sure if I got this right, but:
rgmii-id/txid/rxid is the delay mode between PHY and MAC, right?
on the PHY node it is from the PHY perspective, right?

The errata I have mentioned for am335x say:
"The reset state of RGMII1_IDMODE (bit 4) and RGMII2_IDMODE (bit 5) in
the GMII_SEL register enables internal delay mode on the transmit clock
of the respective RGMII port. The AM335x device does not support
internal delay mode, so RGMII1_IDMODE and RGMII2_IDMODE must be set to 1b."

If the delay mode on the transmit clock is not working on the am335x,
then this translate that the rxid needs to be enabled on the PHY side?

But then why it worked when only the txid was enabled and rxid was not
on the PHY side, and why it works if both txid and rxid is enabled?

Just tried w/ your patch and setting rgmii-rxid for am335x-evmsk and
ethernet is not working, it only works w/ rgmii-id (so both tx and rx
delay is enabled on the PHY side?)

> So considering that this driver seems to be really broken
> (rather then just inverted perspective),
> perhaps we can merge the patch I attached in my previous email after all?
> (Together with a s/rgmii-txid/rgmii-id in the am335x-evmsk.dts.)

at the same time am335x-evm.dts needs to have the same change and most
likely other boards which uses the same PHY needs to be checked?

PS: sorry for my lack of knowledge on the networking stuff...

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Peter Ujfalusi]

Hi Niklas,

On 14/02/2019 14.39, Niklas Cassel wrote:
>>> So, I've rebased your old patch, see attachment.
>>> I suggest that Peter test it on am335x-evm.
>>
>> with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
>> is working.
>> I don't have am335x-evm to test, but it has the same PHY as evmsk.
>>
> 
> Florian's concern was that this PHY driver looked at "phy-mode" from the
> perspective of the MAC rather than the PHY.
> However, if s/rgmii-txid/rgmii-id is the correct fix for am335x-evm,
> then this means that this PHY driver was just broken.
> 
> If the driver had misinterpreted the perspective, then the correct
> fix for am335x-evm would have been s/rgmii-txid/rgmii-rxid.

Not sure if I got this right, but:
rgmii-id/txid/rxid is the delay mode between PHY and MAC, right?
on the PHY node it is from the PHY perspective, right?

The errata I have mentioned for am335x say:
"The reset state of RGMII1_IDMODE (bit 4) and RGMII2_IDMODE (bit 5) in
the GMII_SEL register enables internal delay mode on the transmit clock
of the respective RGMII port. The AM335x device does not support
internal delay mode, so RGMII1_IDMODE and RGMII2_IDMODE must be set to 1b."

If the delay mode on the transmit clock is not working on the am335x,
then this translate that the rxid needs to be enabled on the PHY side?

But then why it worked when only the txid was enabled and rxid was not
on the PHY side, and why it works if both txid and rxid is enabled?

Just tried w/ your patch and setting rgmii-rxid for am335x-evmsk and
ethernet is not working, it only works w/ rgmii-id (so both tx and rx
delay is enabled on the PHY side?)

> So considering that this driver seems to be really broken
> (rather then just inverted perspective),
> perhaps we can merge the patch I attached in my previous email after all?
> (Together with a s/rgmii-txid/rgmii-id in the am335x-evmsk.dts.)

at the same time am335x-evm.dts needs to have the same change and most
likely other boards which uses the same PHY needs to be checked?

PS: sorry for my lack of knowledge on the networking stuff...

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Niklas Cassel]

On Thu, Feb 14, 2019 at 03:22:28PM +0200, Peter Ujfalusi wrote:
> Hi Niklas,
> 
> On 14/02/2019 14.39, Niklas Cassel wrote:
> >>> So, I've rebased your old patch, see attachment.
> >>> I suggest that Peter test it on am335x-evm.
> >>
> >> with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
> >> is working.
> >> I don't have am335x-evm to test, but it has the same PHY as evmsk.
> >>
> > 
> > Florian's concern was that this PHY driver looked at "phy-mode" from the
> > perspective of the MAC rather than the PHY.
> > However, if s/rgmii-txid/rgmii-id is the correct fix for am335x-evm,
> > then this means that this PHY driver was just broken.
> > 
> > If the driver had misinterpreted the perspective, then the correct
> > fix for am335x-evm would have been s/rgmii-txid/rgmii-rxid.
> 
> Not sure if I got this right, but:
> rgmii-id/txid/rxid is the delay mode between PHY and MAC, right?
> on the PHY node it is from the PHY perspective, right?

Yes, from the PHY perspective.

(According to Florian, IIUC, some old PHY drivers were implemented before
it was decided that it is from PHY perspective, rather than from MAC
perspective.)

> 
> The errata I have mentioned for am335x say:
> "The reset state of RGMII1_IDMODE (bit 4) and RGMII2_IDMODE (bit 5) in
> the GMII_SEL register enables internal delay mode on the transmit clock
> of the respective RGMII port. The AM335x device does not support
> internal delay mode, so RGMII1_IDMODE and RGMII2_IDMODE must be set to 1b."
> 
> If the delay mode on the transmit clock is not working on the am335x,
> then this translate that the rxid needs to be enabled on the PHY side?

IIUC what Florian explained, then either MAC or PHY needs to add delays,
so if the PHY only adds delay on e.g. TX, then the MAC needs to add delay
on RX.

However, in your case, the errata says that your MAC is not capable of
adding a delay on TX, therefore the PHY needs to add a delay on TX.

> 
> But then why it worked when only the txid was enabled and rxid was not
> on the PHY side, and why it works if both txid and rxid is enabled?

Because the PHY driver was broken, so the PHY driver always enabled
delays on both TX and RX.

This is how the driver looked before Vinod's change:

        if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
                        phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
                ret = at803x_enable_rx_delay(phydev);
                if (ret < 0)
                        return ret;
        }
 
        if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
                        phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
                ret = at803x_enable_tx_delay(phydev);
                if (ret < 0)
                        return ret;
        }


Yet, the initial value for this PHY is that both TX and RX delay is
enabled, and since this driver never disabled TX/RX delays,
the TX and RX delays were always enabled, no matter what phy-mode
you specified.

> 
> Just tried w/ your patch and setting rgmii-rxid for am335x-evmsk and
> ethernet is not working, it only works w/ rgmii-id (so both tx and rx
> delay is enabled on the PHY side?)
> 
> > So considering that this driver seems to be really broken
> > (rather then just inverted perspective),
> > perhaps we can merge the patch I attached in my previous email after all?
> > (Together with a s/rgmii-txid/rgmii-id in the am335x-evmsk.dts.)
> 
> at the same time am335x-evm.dts needs to have the same change and most
> likely other boards which uses the same PHY needs to be checked?
> 
> PS: sorry for my lack of knowledge on the networking stuff...
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Florian Fainelli]

On 2/14/19 7:06 AM, Niklas Cassel wrote:
> On Thu, Feb 14, 2019 at 03:22:28PM +0200, Peter Ujfalusi wrote:
>> Hi Niklas,
>>
>> On 14/02/2019 14.39, Niklas Cassel wrote:
>>>>> So, I've rebased your old patch, see attachment.
>>>>> I suggest that Peter test it on am335x-evm.
>>>>
>>>> with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
>>>> is working.
>>>> I don't have am335x-evm to test, but it has the same PHY as evmsk.
>>>>
>>>
>>> Florian's concern was that this PHY driver looked at "phy-mode" from the
>>> perspective of the MAC rather than the PHY.
>>> However, if s/rgmii-txid/rgmii-id is the correct fix for am335x-evm,
>>> then this means that this PHY driver was just broken.
>>>
>>> If the driver had misinterpreted the perspective, then the correct
>>> fix for am335x-evm would have been s/rgmii-txid/rgmii-rxid.
>>
>> Not sure if I got this right, but:
>> rgmii-id/txid/rxid is the delay mode between PHY and MAC, right?
>> on the PHY node it is from the PHY perspective, right?
> 
> Yes, from the PHY perspective.
> 
> (According to Florian, IIUC, some old PHY drivers were implemented before
> it was decided that it is from PHY perspective, rather than from MAC
> perspective.)
> 
>>
>> The errata I have mentioned for am335x say:
>> "The reset state of RGMII1_IDMODE (bit 4) and RGMII2_IDMODE (bit 5) in
>> the GMII_SEL register enables internal delay mode on the transmit clock
>> of the respective RGMII port. The AM335x device does not support
>> internal delay mode, so RGMII1_IDMODE and RGMII2_IDMODE must be set to 1b."
>>
>> If the delay mode on the transmit clock is not working on the am335x,
>> then this translate that the rxid needs to be enabled on the PHY side?
> 
> IIUC what Florian explained, then either MAC or PHY needs to add delays,
> so if the PHY only adds delay on e.g. TX, then the MAC needs to add delay
> on RX.
> 
> However, in your case, the errata says that your MAC is not capable of
> adding a delay on TX, therefore the PHY needs to add a delay on TX.

So that mandates specifying either 'rgmii-id' or 'rgmii-txid'.

> 
>>
>> But then why it worked when only the txid was enabled and rxid was not
>> on the PHY side, and why it works if both txid and rxid is enabled?
> 
> Because the PHY driver was broken, so the PHY driver always enabled
> delays on both TX and RX.
> 
> This is how the driver looked before Vinod's change:
> 
>         if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
>                         phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
>                 ret = at803x_enable_rx_delay(phydev);
>                 if (ret < 0)
>                         return ret;
>         }
>  
>         if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
>                         phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
>                 ret = at803x_enable_tx_delay(phydev);
>                 if (ret < 0)
>                         return ret;
>         }
> 
> 
> Yet, the initial value for this PHY is that both TX and RX delay is
> enabled, and since this driver never disabled TX/RX delays,
> the TX and RX delays were always enabled, no matter what phy-mode
> you specified.

Fixing all PHY drivers is probably too much, but since we seem to have
traction and people assigned to QCOM working on this at803x PHY driver,
then let's fix it correctly, I agree with that. So that means:

- disable both RX and TX delay by default
- if RGMII_RXID or RGMII_ID is specified: turn on RX delay
- if RGMII_TXID or RGMII_ID is specified: turn on TX delay

so basically the patch above, with an initial delay disabling for both
RX and TX. Then we fix all DTSes to be correct, at least those in tree
and we provide appropriate Fixes: tag so things get backported
automatically.

How does that sound?
-- 
Florian

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[David Miller]

From: Vinod Koul <vkoul@kernel.org>
Date: Tue, 12 Feb 2019 19:49:22 +0530

> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index 8ff12938ab47..7b54b54e3316 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>  }
>  
> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> +}
> +
> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> +}
> +

Please do not use the inline directive in foo.c files, let the compiler
decide.

Thank you.

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Marc Gonzalez]

On 14/02/2019 17:38, David Miller wrote:

> From: Vinod Koul <vkoul@kernel.org>
> Date: Tue, 12 Feb 2019 19:49:22 +0530
> 
>> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
>> index 8ff12938ab47..7b54b54e3316 100644
>> --- a/drivers/net/phy/at803x.c
>> +++ b/drivers/net/phy/at803x.c
>> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>>  }
>>  
>> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
>> +{
>> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
>> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
>> +}
>> +
>> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
>> +{
>> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
>> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
>> +}
>> +
> 
> Please do not use the inline directive in foo.c files, let the compiler
> decide.

Isn't the compiler free to ignore the "inline" hint?

Regards.

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[David Miller]

From: Marc Gonzalez <marc.w.gonzalez@free.fr>
Date: Thu, 14 Feb 2019 17:46:54 +0100

> On 14/02/2019 17:38, David Miller wrote:
> 
>> From: Vinod Koul <vkoul@kernel.org>
>> Date: Tue, 12 Feb 2019 19:49:22 +0530
>> 
>>> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
>>> index 8ff12938ab47..7b54b54e3316 100644
>>> --- a/drivers/net/phy/at803x.c
>>> +++ b/drivers/net/phy/at803x.c
>>> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>>>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>>>  }
>>>  
>>> +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
>>> +{
>>> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
>>> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
>>> +}
>>> +
>>> +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
>>> +{
>>> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
>>> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
>>> +}
>>> +
>> 
>> Please do not use the inline directive in foo.c files, let the compiler
>> decide.
> 
> Isn't the compiler free to ignore the "inline" hint?

I'm not going into this, but our rules are to not use the inline keyword
except in header files where they are required in order to not emit a
static copy of the function into every file that includes the header.

Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

[Vinod Koul]

On 14-02-19, 08:38, David Miller wrote:
> From: Vinod Koul <vkoul@kernel.org>
> Date: Tue, 12 Feb 2019 19:49:22 +0530
> 
> > diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> > index 8ff12938ab47..7b54b54e3316 100644
> > --- a/drivers/net/phy/at803x.c
> > +++ b/drivers/net/phy/at803x.c
> > @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
> >  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
> >  }
> >  
> > +static inline int at803x_enable_rx_delay(struct phy_device *phydev)
> > +{
> > +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> > +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> > +}
> > +
> > +static inline int at803x_enable_tx_delay(struct phy_device *phydev)
> > +{
> > +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> > +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> > +}
> > +
> 
> Please do not use the inline directive in foo.c files, let the compiler
> decide.

Sure, this was in existing code, will fix up current occurrences as well.

Thanks
-- 
~Vinod