From: Ahmad Fatoum <a.fatoum@pengutronix.de> To: Sascha Hauer <s.hauer@pengutronix.de> Cc: Barebox List <barebox@lists.infradead.org> Subject: Re: [PATCH 1/2] net: designware: eqos: reset phy Date: Tue, 8 Jun 2021 09:31:03 +0200 [thread overview] Message-ID: <2166dc52-64da-14bb-987c-7000c31c6882@pengutronix.de> (raw) In-Reply-To: <20210607222233.GB5267@pengutronix.de> Hello Sascha, On 08.06.21 00:22, Sascha Hauer wrote: > On Mon, Jun 07, 2021 at 05:59:02PM +0200, Ahmad Fatoum wrote: >> Hello Sascha, >> >> On 07.06.21 16:10, Sascha Hauer wrote: >>> 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. >> >>> + >>> + 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. > >> >>> + >>> + 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. >> >>> + 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. > >> >>> + 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. > >> >>> + 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
next prev parent reply other threads:[~2021-06-08 7:32 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-07 14:10 Sascha Hauer 2021-06-07 14:10 ` [PATCH 2/2] net: eqos: Rockchip support Sascha Hauer 2021-06-07 16:05 ` Ahmad Fatoum 2021-06-07 15:59 ` [PATCH 1/2] net: designware: eqos: reset phy Ahmad Fatoum 2021-06-07 22:22 ` Sascha Hauer 2021-06-08 7:31 ` Ahmad Fatoum [this message] 2021-06-08 8:58 ` Sascha Hauer 2021-06-09 8:04 ` Ahmad Fatoum
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