netdev - Re: [PATCH net-next 1/2] ravb: Add tx and rx clock internal delays mode of APSR

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Message-ID: <20170127180701.GA13402@verge.net.au>
Date:   Fri, 27 Jan 2017 19:07:03 +0100
From:   Simon Horman <horms@...ge.net.au>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:     David Miller <davem@...emloft.net>,
        Magnus Damm <magnus.damm@...il.com>, netdev@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
Subject: Re: [PATCH net-next 1/2] ravb: Add tx and rx clock internal delays
 mode of APSR

On Fri, Jan 27, 2017 at 07:55:25PM +0300, Sergei Shtylyov wrote:
> On 01/27/2017 07:49 PM, Simon Horman wrote:
> 
> >>>From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
> >>>
> >>>This patch enables tx and rx clock internal delay modes (TDM and RDM).
> >>>
> >>>This is to address a failure in the case of 1Gbps communication using the
> >>>by salvator-x board with the KSZ9031RNX phy. This has been reported to
> >>>occur with both the r8a7795 (H3) and r8a7796 (M3-W) SoCs.
> >>>
> >>>With this change APSR internal delay modes are enabled for
> >>>"rgmii-id", "rgmii-rxid" and "rgmii-txid" phy modes as follows:
> >>>
> >>>phy mode   | ASPR delay mode
> >>>-----------+----------------
> >>>rgmii-id   | TDM and RDM
> >>>rgmii-rxid | RDM
> >>>rgmii-txid | TDM
> >>>
> >>>Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
> >>>Signed-off-by: Simon Horman <horms+renesas@...ge.net.au>
> >>>
> >>>---
> >>>v1 [Simon Horman]
> >>>- Combined patches
> >>>- Reworded changelog
> >>>
> >>>v0 [Kazuya Mizuguchi]
> >>>---
> >>>drivers/net/ethernet/renesas/ravb.h      | 10 ++++++++++
> >>>drivers/net/ethernet/renesas/ravb_main.c | 29 +++++++++++++++++++++++++++++
> >>>2 files changed, 39 insertions(+)
> >>>
> >>>diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> >>>index f1109661a533..d7c91d48cc48 100644
> >>>--- a/drivers/net/ethernet/renesas/ravb.h
> >>>+++ b/drivers/net/ethernet/renesas/ravb.h
> >>[...]
> >>>@@ -248,6 +249,15 @@ enum ESR_BIT {
> >>>	ESR_EIL		= 0x00001000,
> >>>};
> >>>
> >>>+/* APSR */
> >>>+enum APSR_BIT {
> >>>+	APSR_MEMS		= 0x00000002,
> >>
> >>   Not documented in the revision 0.5 of the gen3 manual...
> >
> >It is in version 0.53 of the documentation but I think it can be dropped
> >from this patch as its unused.
> 
>    No need to drop, let it be. :-)
> 
> >>>+	APSR_CMSW		= 0x00000010,
> >
> >I think the above can also be dropped as it is unused.
> 
>    No need.

Ok, lets leave it and MEMS.

> >>>+	APSR_DM			= 0x00006000,
> >>
> >>   ... and neither this field. Are these documented in the latter revs?
> >
> >This one is not. I can ask Mizuguchi-san to confirm it exists (with himself).
> 
>    The whole patch depends on it! If it's not documented, I'd like a comment
> added, like I did for the other undocumented things in this driver...

Sure.

> [...]
> >>>diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> >>>index 89ac1e3f6175..9fb4c04c5885 100644
> >>>--- a/drivers/net/ethernet/renesas/ravb_main.c
> >>>+++ b/drivers/net/ethernet/renesas/ravb_main.c
> >>>@@ -1904,6 +1904,29 @@ static void ravb_set_config_mode(struct net_device *ndev)
> >>>	}
> >>>}
> >>>
> >>>+static void ravb_set_delay_mode(struct net_device *ndev)
> >>>+{
> >>>+	struct ravb_private *priv = netdev_priv(ndev);
> >>>+
> >>>+	if (priv->chip_id != RCAR_GEN2) {
> >>>+		switch (priv->phy_interface) {
> >>>+		case PHY_INTERFACE_MODE_RGMII_ID:
> >>>+			ravb_modify(ndev, APSR, APSR_DM, APSR_DM_RDM |
> >>>+				   APSR_DM_TDM);
> >>>+			break;
> >>>+		case PHY_INTERFACE_MODE_RGMII_RXID:
> >>>+			ravb_modify(ndev, APSR, APSR_DM, APSR_DM_RDM);
> >>>+			break;
> >>>+		case PHY_INTERFACE_MODE_RGMII_TXID:
> >>>+			ravb_modify(ndev, APSR, APSR_DM, APSR_DM_TDM);
> >>>+			break;
> >>>+		default:
> >>>+			ravb_modify(ndev, APSR, APSR_DM, 0);
> >>>+			break;
> >>>+		}
> >>
> >>   How about doing ravb_modify() only once?
> >
> >Something like this?
> >
> >		int set = 0;
> >
> >		if (priv->phy_interface == PHY_INTERFACE_MODE_RGMII_ID ||
> >		    priv->phy_interface == PHY_INTERFACE_MODE_RGMII_RXID)
> >		    set |= APSR_DM_RDM;
> >
> >		if (priv->phy_interface == PHY_INTERFACE_MODE_RGMII_ID ||
> >		    priv->phy_interface == PHY_INTERFACE_MODE_RGMII_TXID)
> >		    set |= APSR_DM_TDM;
> >
> >		ravb_modify(ndev, APSR, APSR_DM, set);
> >
> >I don't really see any advantage to it but I can change things around
> >however you like.
> 
>    I didn't mean to replace *switch*, actually -- just to move ravb_modify()
> out of it.

Ok, I will make it so.