Re: [PATCH 1/2] net: designware: eqos: reset phy
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
Date: 2021-06-08 07:32:35
Hello Sascha, On 08.06.21 00:22, Sascha Hauer wrote:
On Mon, Jun 07, 2021 at 05:59:02PM +0200, Ahmad Fatoum wrote:quoted
Hello Sascha, On 07.06.21 16:10, Sascha Hauer wrote:quoted
The designware eqos DT binding has support for specifying reset GPIOs. Add support for them. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> --- drivers/net/designware_eqos.c | 33 +++++++++++++++++++++++++++++++++ drivers/of/of_gpio.c | 7 +++++++ 2 files changed, 40 insertions(+)diff --git a/drivers/net/designware_eqos.c b/drivers/net/designware_eqos.c index d2baaeaf63..0321024169 100644 --- a/drivers/net/designware_eqos.c +++ b/drivers/net/designware_eqos.c@@ -8,9 +8,11 @@ #include <common.h> #include <init.h> +#include <gpio.h> #include <dma.h> #include <net.h> #include <of_net.h> +#include <of_gpio.h> #include <linux/iopoll.h> #include <linux/time.h> #include <linux/sizes.h>@@ -189,6 +191,33 @@ struct eqos_desc { #define MII_BUSY (1 << 0) +static int eqos_phy_reset(struct device_d *dev, struct eqos *eqos) +{ + int phy_reset; + int ret; + u32 delays[3] = { 0, 0, 0 }; + + phy_reset = of_get_named_gpio(dev->device_node, "snps,reset-gpio", 0); + + if (!gpio_is_valid(phy_reset)) + return 0;Whitespace is wrong.quoted
+ + ret = gpio_request(phy_reset, "phy-reset"); + if (ret) + return ret;Can you use gpiod_get instead? This would reduce the boilerplate here.Sure. I didn't realize I don't honour the active high/low flags the way I did it.quoted
quoted
+ + of_property_read_u32_array(dev->device_node, + "snps,reset-delays-us", + delays, ARRAY_SIZE(delays)); +Looks strange to read out a delay and not act on it. I'd prefer waiting delays[0] here.Yes, it looks strange, but that's because the binding doesn't make much sense. Why should I insert a delay before doing anything?
.--------.
POR --------->|R flip |---- Regulator ----> PHY VDD
.->|S flop |
| `--------'
|
|
|
RESET GPIO -----'`-------------------------------> PHY Reset
(active low)
It's stupid, but it works with Linux and wouldn't with barebox
(if PHY VDD takes too long to stabilize)... ^^'
I can a delay here, it wouldn't make much difference as all users except one specify zero delay here anyway. For the one exception I would bet someone has inserted the first delay without a good reason, they are all 10000.
That's probably true. I still think mimicking Linux' interpretation of bindings is a good general rule to follow.
quoted
quoted
+ gpio_direction_active(phy_reset, 0);This always sets logical zero, because gpio_request above doesn't accept a flag telling it otherwise. You'll need of_get_named_gpio_flags here, at which point, you'll have basically open-coded gpiod_get(), so you could use that.Right.quoted
quoted
+ udelay(delays[1]);Linux rounds up to 1 msec granularity here. We should do likewise.I don't see a good reason for that. The Linux driver used udelay() initially, that was changed to msleep as the times were too long for busy waiting. I have no clue why the author didn't use usleep_range instead.
Same reason: Device trees are tested with Linux. They've a better chance of just working when we round up wait times the same way.
quoted
quoted
+ gpio_set_active(phy_reset, 1);Nitpick: true/false.Ok. Sascha
-- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox