From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH 2/4] ravb: Add optional PHY reset during system resume Date: Sat, 30 Sep 2017 23:23:42 +0300 Message-ID: <47456e34-2c2f-ec19-fcda-e3132a8037b3@cogentembedded.com> References: <1506614014-4398-1-git-send-email-geert+renesas@glider.be> <1506614014-4398-3-git-send-email-geert+renesas@glider.be> <406f7aff-e386-31f3-39d3-17523443c265@gmail.com> <1a474c45-29ea-82fa-1ab0-0febfdc38bcb@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Geert Uytterhoeven , "David S . Miller" , Simon Horman , Magnus Damm , Andrew Lunn , =?UTF-8?Q?Niklas_S=c3=b6derlund?= , "netdev@vger.kernel.org" , Linux-Renesas , "devicetree@vger.kernel.org" To: Florian Fainelli , Geert Uytterhoeven Return-path: In-Reply-To: <1a474c45-29ea-82fa-1ab0-0febfdc38bcb@gmail.com> Content-Language: en-MW Sender: linux-renesas-soc-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hello! On 09/28/2017 10:21 PM, Florian Fainelli wrote: >>>> If the optional "reset-gpios" property is specified in DT, the generic >>>> MDIO bus code takes care of resetting the PHY during device probe. >>>> However, the PHY may still have to be reset explicitly after system >>>> resume. >>>> >>>> This allows to restore Ethernet operation after resume from s2ram on >>>> Salvator-XS, where the enable pin of the regulator providing PHY power >>>> is connected to PRESETn, and PSCI suspend powers down the SoC. >>>> >>>> Signed-off-by: Geert Uytterhoeven >>>> --- >>>> drivers/net/ethernet/renesas/ravb_main.c | 9 +++++++++ >>>> 1 file changed, 9 insertions(+) >>>> >>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c >>>> index fdf30bfa403bf416..96d1d48e302f8c9a 100644 >>>> --- a/drivers/net/ethernet/renesas/ravb_main.c >>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c [...] >>>> @@ -2302,6 +2304,13 @@ static int __maybe_unused ravb_resume(struct device *dev) >>>> * reopen device if it was running before system suspended. >>>> */ >>>> >>>> + /* PHY reset */ >>>> + if (bus->reset_gpiod) { >>>> + gpiod_set_value_cansleep(bus->reset_gpiod, 1); >>>> + udelay(bus->reset_delay_us); >>>> + gpiod_set_value_cansleep(bus->reset_gpiod, 0); >>>> + } >>> >>> This is a clever hack, but unfortunately this is also misusing the MDIO >>> bus reset line into a PHY reset line. As commented in patch 3, if this >>> reset line is tied to the PHY, then this should be a PHY property and >> >> OK. >> >>> you cannot (ab)use the MDIO bus GPIO reset logic anymore... >> >> And then I should add reset-gpios support to drivers/net/phy/micrel.c? >> Or is there already generic code to handle per-PHY reset? I couldn't find it. > > There is not such a thing unfortunately, but it would presumably be It's strange you don't remember about my (abandoned) patches to handle per=PHY reset GPIOs -- perhaps it's time to unearth them. Here they are: http://patchwork.ozlabs.org/patch/616495/ http://patchwork.ozlabs.org/patch/616501/ I had v3 in the works before abandoning this series -- it doesn't apply now. > called within drivers/net/phy/mdio_bus.c during bus->reset() time > because you need the PHY reset to be deasserted before you can > successfully read/write from the PHY, and if you can't read/write from > the PHY, the MDIO bus layer cannot read the PHY ID, and therefore cannot > match a PHY device with its driver, so things don't work. I did this a bit differently... [...] MBR, Sergei