Re: [PATCH 1/2] net: ethernet: nb8800: Do not apply TX delay at MAC level

Hi Andrew,

On 11/04/2016 04:11 PM, Andrew Lunn wrote:

On Fri, Nov 04, 2016 at 04:02:24PM +0100, Sebastian Frias wrote:

quoted

The delay can be applied at PHY or MAC level, but since
PHY drivers will apply the delay at PHY level when using
one of the "internal delay" declinations of RGMII mode
(like PHY_INTERFACE_MODE_RGMII_TXID), applying it again
at MAC level causes issues.

Signed-off-by: Sebastian Frias <redacted>
---
 drivers/net/ethernet/aurora/nb8800.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c
index b59aa35..d2855c9 100644
--- a/drivers/net/ethernet/aurora/nb8800.c
+++ b/drivers/net/ethernet/aurora/nb8800.c

@@ -1282,7 +1282,7 @@ static int nb8800_tangox_init(struct net_device *dev)
 		break;
 
 	case PHY_INTERFACE_MODE_RGMII_TXID:
-		pad_mode = PAD_MODE_RGMII | PAD_MODE_GTX_CLK_DELAY;
+		pad_mode = PAD_MODE_RGMII;
 		break;

How many boards use this Ethernet driver? How many boards are your
potentially breaking, because they need this delay?

This part is specific to the Tango architecture, as noted by the
function name "nb8800_tangox_init".

Also the register used here is Sigma-specific (i.e.: not related to the
Aurora VLSI MAC, "au-nb8800")

The thing is that without this patch if we set
phy-connection-type="rgmii-txid" on the DT, then both, the PHY and the
MAC, will apply the delay.

Best regards,

Sebastian

I guess it is a small number, because doesn't it require the PHY is
also broken, not adding a delay when it should?

     Andrew