From: Andrew Lunn <andrew@lunn•ch>
To: Andy Duan <fugang.duan@nxp•com>
Cc: Leonard Crestez <leonard.crestez@nxp•com>,
David Miller <davem@davemloft•net>,
netdev <netdev@vger•kernel.org>,
Chris Healy <Chris.Healy@zii•aero>,
dl-linux-imx <linux-imx@nxp•com>, Chris Healy <cphealy@gmail•com>
Subject: Re: [EXT] Re: [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with polled IO
Date: Tue, 28 Apr 2020 15:34:45 +0200 [thread overview]
Message-ID: <20200428133445.GA21352@lunn.ch> (raw)
In-Reply-To: <HE1PR0402MB2745B6388B6BF7306629A305FFAC0@HE1PR0402MB2745.eurprd04.prod.outlook.com>
> Andrew, after investigate the issue, there have one MII event coming later then
> clearing MII pending event when writing MSCR register (MII_SPEED).
>
> Check the rtl design by co-working with our IC designer, the MII event generation
> condition:
> - writing MSCR:
> - mmfr[31:0]_not_zero & mscr[7:0]_is_zero & mscr_reg_data_in[7:0] != 0
> - writing MMFR:
> - mscr[7:0]_not_zero
>
> mmfr[31:0]: current MMFR register value
> mscr[7:0]: current MSCR register value
> mscr_reg_data_in[7:0]: the value wrote to MSCR
>
>
> Below patch can fix the block issue:
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -2142,6 +2142,15 @@ static int fec_enet_mii_init(struct platform_device *pdev)
> if (suppress_preamble)
> fep->phy_speed |= BIT(7);
>
> + /*
> + * Clear MMFR to avoid to generate MII event by writing MSCR.
> + * MII event generation condition:
> + * - writing MSCR:
> + * - mmfr[31:0]_not_zero & mscr[7:0]_is_zero & mscr_reg_data_in[7:0] != 0
> + * - writing MMFR:
> + * - mscr[7:0]_not_zero
> + */
> + writel(0, fep->hwp + FEC_MII_DATA);
> writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
Hi Andy
Thanks for digging into the internal of the FEC. Just to make sure i
understand this correctly:
In fec_enet_mii_init() we have:
holdtime = DIV_ROUND_UP(clk_get_rate(fep->clk_ipg), 100000000) - 1;
fep->phy_speed = mii_speed << 1 | holdtime << 8;
writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
/* Clear any pending transaction complete indication */
writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
You are saying this write to the FEC_MII_SPEED register can on some
SoCs trigger an FEC_ENET_MII event. And because it does not happen
immediately, it happens after the clear which is performed here?
Sometime later we then go into fec_enet_mdio_wait(), the event is
still pending, so we read the FEC_MII_DATA register too early?
But this does not fully explain the problem. This should only affect
the first MDIO transaction, because as we exit fec_enet_mdio_wait()
the event is cleared. But Leonard reported that all reads return 0,
not just the first.
Andrew
next prev parent reply other threads:[~2020-04-28 13:34 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 0:45 [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with polled IO Andrew Lunn
2020-04-14 3:07 ` [EXT] " Andy Duan
2020-04-14 3:49 ` Andrew Lunn
2020-04-14 5:12 ` Andy Duan
2020-04-14 12:55 ` Andrew Lunn
2020-04-14 23:38 ` David Miller
2020-04-15 0:20 ` Andrew Lunn
2020-04-27 15:19 ` Leonard Crestez
2020-04-27 15:29 ` Andy Duan
2020-04-27 15:37 ` Andrew Lunn
2020-04-27 16:37 ` Andrew Lunn
2020-04-27 16:48 ` Fabio Estevam
2020-04-27 16:46 ` Andrew Lunn
2020-04-27 17:48 ` [EXT] " Andy Duan
2020-04-27 20:00 ` Leonard Crestez
2020-04-27 20:13 ` Andrew Lunn
2020-04-28 7:50 ` [EXT] " Andy Duan
2020-04-28 13:34 ` Andrew Lunn [this message]
2020-04-28 13:50 ` Andy Duan
2020-04-28 14:29 ` Andrew Lunn
-- strict thread matches above, loose matches on Subject: below --
2020-10-20 2:14 Greg Ungerer
2020-10-20 2:40 ` Andrew Lunn
2020-10-20 3:02 ` [EXT] " Andy Duan
2020-10-20 13:06 ` Chris Healy
2020-10-20 13:52 ` Andy Duan
2020-10-20 13:08 ` Andrew Lunn
2020-10-21 1:51 ` Greg Ungerer
2020-10-21 2:19 ` [EXT] " Andy Duan
2020-10-21 2:37 ` Greg Ungerer
2020-10-21 13:37 ` Andrew Lunn
2020-10-22 1:14 ` Greg Ungerer
2020-10-22 2:39 ` [EXT] " Andy Duan
2020-10-22 9:04 ` Andy Duan
2020-10-27 0:17 ` Greg Ungerer
2020-10-27 1:33 ` Andy Duan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200428133445.GA21352@lunn.ch \
--to=andrew@lunn$(echo .)ch \
--cc=Chris.Healy@zii$(echo .)aero \
--cc=cphealy@gmail$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=fugang.duan@nxp$(echo .)com \
--cc=leonard.crestez@nxp$(echo .)com \
--cc=linux-imx@nxp$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox