From: Florian Fainelli <f.fainelli@gmail.com>
To: Roger Quadros <rogerq@ti.com>,
davem@davemloft.net, Andrew Lunn <andrew@lunn.ch>
Cc: tony@atomide.com, nsekhar@ti.com, jsarha@ti.com,
netdev@vger.kernel.org, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 net-next] mdio_bus: Issue GPIO RESET to PHYs.
Date: Thu, 20 Apr 2017 18:23:41 -0700 [thread overview]
Message-ID: <fa24ae98-3d4f-4b11-bbb4-485b9ed41ed7@gmail.com> (raw)
In-Reply-To: <f372db02-a919-55b4-9200-20726cd13482@ti.com>
Hi Roger,
On 04/20/2017 07:11 AM, Roger Quadros wrote:
> Some boards [1] leave the PHYs at an invalid state
> during system power-up or reset thus causing unreliability
> issues with the PHY which manifests as PHY not being detected
> or link not functional. To fix this, these PHYs need to be RESET
> via a GPIO connected to the PHY's RESET pin.
>
> Some boards have a single GPIO controlling the PHY RESET pin of all
> PHYs on the bus whereas some others have separate GPIOs controlling
> individual PHY RESETs.
>
> In both cases, the RESET de-assertion cannot be done in the PHY driver
> as the PHY will not probe till its reset is de-asserted.
> So do the RESET de-assertion in the MDIO bus driver.
>
> [1] - am572x-idk, am571x-idk, a437x-idk
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
A few comments on the binding and the code, sorry for this late review.
> +Example :
> +This example shows these optional properties, plus other properties
> +required for the TI Davinci MDIO driver.
> +
> + davinci_mdio: ethernet@0x5c030000 {
> + compatible = "ti,davinci_mdio";
> + reg = <0x5c030000 0x1000>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
> + reset-delay-us = <2>; /* PHY datasheet states 1uS min */
us is micro seconds, uS is micro siemens.
> +
> + ethphy0: ethernet-phy@1 {
> + reg = <1>;
> + };
> +
> + ethphy1: ethernet-phy@3 {
> + reg = <3>;
> + };
> + };
>
> + /* de-assert bus level PHY GPIO resets */
> + for (i = 0; i < bus->num_reset_gpios; i++) {
> + gpiod = devm_gpiod_get_index(&bus->dev, "reset", i,
> + GPIOD_OUT_LOW);
> + if (IS_ERR(gpiod)) {
> + err = PTR_ERR(gpiod);
> + if (err != -ENOENT) {
> + pr_err("mii_bus %s couldn't get reset GPIO\n",
> + bus->id);
Could we use dev_err(&bus->dev) here to better identify which MDIO bus
is returning the problem?
> + return err;
Should we somehow "unwind" the reset lines we were able to successfully
take out of reset and therefore put back into reset state? How about
mdiobus_unregister()? Should we have similar code there, if not for
correctness to be more power efficient?
> + }
> + } else {
> + gpiod_set_value_cansleep(gpiod, 1);
> + udelay(bus->reset_delay_us);
> + gpiod_set_value_cansleep(gpiod, 0);
Does that work even if the polarity of the reset line is active low?
Thanks!
--
Florian
next prev parent reply other threads:[~2017-04-21 1:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-05 8:33 [PATCH] net: davinci_mdio: add GPIO reset logic Roger Quadros
2017-04-05 15:03 ` Andrew Lunn
2017-04-06 9:15 ` Roger Quadros
2017-04-06 12:05 ` Andrew Lunn
2017-04-06 16:48 ` Roger Quadros
2017-04-08 13:55 ` David Miller
2017-04-08 15:10 ` Andrew Lunn
2017-04-08 15:18 ` Florian Fainelli
2017-04-10 7:52 ` Roger Quadros
2017-04-19 9:24 ` [PATCH] mdio_bus: Issue GPIO RESET to PHYs Roger Quadros
2017-04-19 11:39 ` Andrew Lunn
2017-04-19 11:56 ` Roger Quadros
2017-04-19 13:38 ` Andrew Lunn
2017-04-20 7:58 ` Roger Quadros
2017-04-20 8:39 ` [PATCH v2] " Roger Quadros
2017-04-20 13:13 ` Andrew Lunn
2017-04-20 13:56 ` Roger Quadros
2017-04-20 14:11 ` [PATCH v3 net-next] " Roger Quadros
2017-04-21 1:12 ` Andrew Lunn
2017-04-21 1:23 ` Florian Fainelli [this message]
2017-04-21 1:38 ` Andrew Lunn
2017-04-21 8:04 ` Roger Quadros
2017-04-21 13:15 ` [PATCH v4 " Roger Quadros
2017-04-21 13:31 ` Lars-Peter Clausen
2017-04-23 23:35 ` Andrew Lunn
2017-04-24 9:04 ` Roger Quadros
2017-04-24 16:32 ` Florian Fainelli
2017-04-25 16:22 ` Lars-Peter Clausen
2017-04-25 16:31 ` Florian Fainelli
2017-04-26 10:46 ` Roger Quadros
2017-04-26 12:27 ` Andrew Lunn
2017-04-26 10:43 ` Roger Quadros
2017-04-24 16:40 ` David Miller
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