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

Hi Måns,

On 11/04/2016 04:18 PM, Måns Rullgård wrote:

Sebastian Frias [off-list ref] writes:

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.

The Broadcom GENET driver does the same thing.

Well, I don't know who uses that driver, or why they did it that way.

However, with the current code and DT bindings, if one requires
the delay, phy-connection-type="rgmii-txid" must be set.

But when doing so, both the Atheros 8035 and the Aurora NB8800 drivers
will apply the delay.

I think a better way of dealing with this is that both, PHY and MAC
drivers exchange information so that the delay is applied only once.

I can see how to do that in another patch set.

quoted

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;

 	default:

-- 
1.7.11.2

If this change is correct (and I'm not convinced it is), that case
should be merged with the one above it and PHY_INTERFACE_MODE_RGMII_RXID
added as well.

I can do a single patch.

The reason I made two patches was that it was clear what this patch
does, i.e.: do not apply the delay at MAC level, and what the subsequent
patch does, i.e.: handle all RGMII declinations.

Best regards,

Sebastian