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Message-ID: <159283956449.1456598.3334254941386336677@kwain>
Date: Mon, 22 Jun 2020 17:26:04 +0200
From: Antoine Tenart <antoine.tenart@...tlin.com>
To: Quentin Schulz <foss@...il.net>
Cc: davem@...emloft.net, andrew@...n.ch, f.fainelli@...il.com,
hkallweit1@...il.com, richardcochran@...il.com,
alexandre.belloni@...tlin.com, UNGLinuxDriver@...rochip.com,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
thomas.petazzoni@...tlin.com, allan.nielsen@...rochip.com
Subject: Re: [PATCH net-next v3 5/8] net: phy: mscc: 1588 block initialization
Hi Quentin,
Quoting Quentin Schulz (2020-06-21 18:57:14)
>
> Feels weird to review my own patches a year later having written them,
> almost nostalgic :)
:)
> On 2020-06-19 14:22, Antoine Tenart wrote:
> [...]
> > @@ -373,6 +374,21 @@ struct vsc8531_private {
> > unsigned long ingr_flows;
> > unsigned long egr_flows;
> > #endif
> > +
> > + bool input_clk_init;
> > + struct vsc85xx_ptp *ptp;
> > +
> > + /* For multiple port PHYs; the MDIO address of the base PHY in the
> > + * pair of two PHYs that share a 1588 engine. PHY0 and PHY2 are
> > coupled.
> > + * PHY1 and PHY3 as well. PHY0 and PHY1 are base PHYs for their
> > + * respective pair.
> > + */
> > + unsigned int ts_base_addr;
> > + u8 ts_base_phy;
> > +
>
> I hate myself now for this bad naming. After reading the code,
> ts_base_addr is the address
> of the base PHY (of a pair) on the MDIO bus and ts_base_phy is the
> "internal" (package)
> address of the base PHy (of a pair). This is not very explicit.
>
> Would ts_base_phy renamed into a ts_base_pkg_addr work better?
>
> > + /* ts_lock: used for per-PHY timestamping operations.
> > + */
>
> I don't remember exactly the comment best practices in net anymore, but
> one line
> comment instead?
If you look at next patches, you'll see the comment is then multi-lines,
as other members are added to the structure. I'll fix it anyway.
> [...]
>
> > #endif /* _MSCC_PHY_H_ */
> > diff --git a/drivers/net/phy/mscc/mscc_main.c
> > b/drivers/net/phy/mscc/mscc_main.c
> > index 052a0def6e83..87ddae514627 100644
> > --- a/drivers/net/phy/mscc/mscc_main.c
> > +++ b/drivers/net/phy/mscc/mscc_main.c
> > @@ -1299,11 +1299,29 @@ static void vsc8584_get_base_addr(struct
> > phy_device *phydev)
> > __phy_write(phydev, MSCC_EXT_PAGE_ACCESS, MSCC_PHY_PAGE_STANDARD);
> > mutex_unlock(&phydev->mdio.bus->mdio_lock);
> >
> > - if (val & PHY_ADDR_REVERSED)
> > + /* In the package, there are two pairs of PHYs (PHY0 + PHY2 and
> > + * PHY1 + PHY3). The first PHY of each pair (PHY0 and PHY1) is
> > + * the base PHY for timestamping operations.
> > + */
> > + if (val & PHY_ADDR_REVERSED) {
> > vsc8531->base_addr = phydev->mdio.addr + addr;
> > - else
> > + vsc8531->ts_base_addr = phydev->mdio.addr;
> > + vsc8531->ts_base_phy = addr;
> > + if (addr > 1) {
> > + vsc8531->ts_base_addr += 2;
> > + vsc8531->ts_base_phy += 2;
> > + }
> > + } else {
> > vsc8531->base_addr = phydev->mdio.addr - addr;
> >
> > + vsc8531->ts_base_addr = phydev->mdio.addr;
> > + vsc8531->ts_base_phy = addr;
>
> The two lines above are identical in both conditions, what about moving
> them just before the if (val & PHY_ADDR_REVERSED) line?
That's right, I'll fix it for v4.
> [...]
>
> > +static const u32 vsc85xx_egr_latency[] = {
> > + /* Copper Egress */
> > + 1272, /* 1000Mbps */
> > + 12516, /* 100Mbps */
> > + 125444, /* 10Mbps */
> > + /* Fiber Egress */
> > + 1277, /* 1000Mbps */
> > + 12537, /* 100Mbps */
> > + /* Copper Egress when MACsec ON */
> > + 3496, /* 1000Mbps */
> > + 34760, /* 100Mbps */
> > + 347844, /* 10Mbps */
> > + /* Fiber Egress when MACsec ON */
> > + 3502, /* 1000Mbps */
> > + 34780, /* 100Mbps */
> > +};
> > +
> > +static const u32 vsc85xx_ingr_latency[] = {
> > + /* Copper Ingress */
> > + 208, /* 1000Mbps */
> > + 304, /* 100Mbps */
> > + 2023, /* 10Mbps */
> > + /* Fiber Ingress */
> > + 98, /* 1000Mbps */
> > + 197, /* 100Mbps */
> > + /* Copper Ingress when MACsec ON */
> > + 2408, /* 1000Mbps */
> > + 22300, /* 100Mbps */
> > + 222009, /* 10Mbps */
> > + /* Fiber Ingress when MACsec ON */
> > + 2299, /* 1000Mbps */
> > + 22192, /* 100Mbps */
> > +};
> > +
>
> Wouldn't it make more sense to separate the latencies into two different
> arrays? One for non-MACsec and one with? No idx "hack" later in the
> function that way.
Removing the "idx += 5" means having an added logic on the struct to
used to retrieve the delay (I'll use two extra variables). But I do
agree because that will improve the latency definition, and that alone
is better.
> [...]
>
> > +static int vsc85xx_eth1_conf(struct phy_device *phydev, enum ts_blk
> > blk,
> > + bool enable)
> > +{
> > + struct vsc8531_private *vsc8531 = phydev->priv;
> > + u32 val = ANA_ETH1_FLOW_ADDR_MATCH2_DEST;
> > +
> > + if (vsc8531->ptp->rx_filter == HWTSTAMP_FILTER_PTP_V2_L2_EVENT) {
> > + /* PTP over Ethernet multicast address for SYNC and DELAY msg */
> > + u8 ptp_multicast[6] = {0x01, 0x1b, 0x19, 0x00, 0x00, 0x00};
> > +
>
> I think this is actually part of "the" standard:
> https://en.wikipedia.org/wiki/Precision_Time_Protocol#Message_transport
>
> So would it make sense to make it available to all drivers via one of
> the
> include/linux/ptp_*.h?
That's right. I had a look and only two drivers (including this one)
seems to be using the PTP over Ethernet multicast address. Also that
would mean adding a new header (there are none, to my knowledge, where
this would fit) for a single line definition.
I don't know, I believe this is a good idea, but maybe a bit to early?
> [...]
>
> > +static bool vsc8584_is_1588_input_clk_configured(struct phy_device
> > *phydev)
> > +{
> > + struct vsc8531_private *vsc8531 = phydev->priv;
> > +
> > + if (vsc8531->ts_base_addr != phydev->mdio.addr) {
> > + struct mdio_device *dev;
> > +
> > + dev = phydev->mdio.bus->mdio_map[vsc8531->ts_base_addr];
> > + phydev = container_of(dev, struct phy_device, mdio);
> > + vsc8531 = phydev->priv;
> > + }
> > +
> > + return vsc8531->input_clk_init;
> > +}
> > +
> > +static void vsc8584_set_input_clk_configured(struct phy_device
> > *phydev)
> > +{
> > + struct vsc8531_private *vsc8531 = phydev->priv;
> > +
> > + if (vsc8531->ts_base_addr != phydev->mdio.addr) {
> > + struct mdio_device *dev;
> > +
> > + dev = phydev->mdio.bus->mdio_map[vsc8531->ts_base_addr];
> > + phydev = container_of(dev, struct phy_device, mdio);
> > + vsc8531 = phydev->priv;
> > + }
> > +
> > + vsc8531->input_clk_init = true;
> > +}
>
> Duplicated code here.
> Maybe:
>
> static struct vsc8531_private * vsc8584_get_ts_base_phydev(struct
> phy_device *phydev)
> {
> struct vsc8531_private *vsc8531 = phydev->priv;
> if (vsc8531->ts_base_addr != phydev->mdio.addr) {
> struct mdio_device *dev;
>
> dev = phydev->mdio.bus->mdio_map[vsc8531->ts_base_addr];
> phydev = container_of(dev, struct phy_device, mdio);
> vsc8531 = phydev->priv;
> }
> return vsc8531;
> }
I'll do something of the like for v4. I'll still keep the is_configured
and set_configured helpers as I don't want to expose the base PHY
private structure outside of those helpers.
> [...]
>
> > diff --git a/drivers/net/phy/mscc/mscc_ptp.h
> > b/drivers/net/phy/mscc/mscc_ptp.h
> [...]
> > +
> > +struct vsc85xx_ptphdr {
> > + u8 tsmt; /* transportSpecific | messageType */
> > + u8 ver; /* reserved0 | versionPTP */
> > + __be16 msglen;
> > + u8 domain;
> > + u8 rsrvd1;
> > + __be16 flags;
> > + __be64 correction;
> > + __be32 rsrvd2;
> > + __be64 clk_identity;
> > + __be16 src_port_id;
> > + __be16 seq_id;
> > + u8 ctrl;
> > + u8 log_interval;
> > +} __attribute__((__packed__));
> > +
>
> AFAICT, this is also part of "the" standard:
> http://wiki.hevs.ch/uit/index.php5/Standards/Ethernet_PTP/frames#PTP_Header
> Would maybe be better to have it in one of the header files in include/?
Having common definitions when multiple drivers do use the same struct,
or defined values is good. However if like here it is used in a single
driver, and especially for this kind of representation, I don't believe
that would add any value.
Thanks,
Antoine
--
Antoine Ténart, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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