From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: Re: [PATCH 1/3] fixed_phy: handle link-down case Date: Fri, 17 Jul 2015 15:01:53 -0700 Message-ID: <55A97B51.3030508@gmail.com> References: <55A7C45F.1070501@list.ru> <55A7C49E.2020803@list.ru> <55A83D86.2030505@gmail.com> <55A8E64A.3040009@list.ru> <55A94E5A.9010104@gmail.com> <55A95F83.8010900@list.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Linux kernel , Sebastien Rannou , Arnaud Ebalard , Stas Sergeev To: Stas Sergeev , netdev Return-path: In-Reply-To: <55A95F83.8010900@list.ru> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 17/07/15 13:03, Stas Sergeev wrote: > 17.07.2015 21:50, Florian Fainelli =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 17/07/15 04:26, Stas Sergeev wrote: >>> 17.07.2015 02:25, Florian Fainelli =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> On 16/07/15 07:50, Stas Sergeev wrote: >>>>> Currently fixed_phy driver recognizes only the link-up state. >>>>> This simple patch adds an implementation of link-down state. >>>>> It fixes the status registers when link is down, and also allows >>>>> to register the fixed-phy with link down without specifying the s= peed. >>>> This patch still breaks my setups here, e.g: drivers/net/dsa/bcm_s= f2.c, >>>> but I will look into it. >>>> >>>> Do we really need this for now for your two other patches to work >>>> properly, or is it just nicer to have? >>> Yes, absolutely. >>> Otherwise registering fixed phy will return -EINVAL >>> because of the missing link speed (even though the link >>> is down). >> Ok, I see the problem that you have now. Arguably you could say that >> according to the fixed-link binding, speed needs to be specified and= the >> code correctly errors out with such an error if you do not specify i= t. I > Aren't you missing the fact that .link=3D0? > I think what you say is true only for the link-up case, no? > .speed=3D=3D0 is valid for link-down IMHO: no link - zero speed. Pardon me being very dense and stupid here, but your problem is that th= e "speed" parameter is not specified in your DT, and we end-up returning -EINVAL from of_phy_register_fixed_link(), is that what is happening? And even if we silenced that error, we would end-up calling fixed_phy_add() which would also return -EINVAL because then, we would have status.link =3D 1, but no speed. So I better understand what is it that you are after here, and that is also a broken Device Tree, is not it? So this was the reason why in earlier versions of the patchset you ended-up with a given speed which would make us pass this condition, ri= ght? >=20 >> So is different is that I use a link_update callback, and so we rely= on >> at least one call of this function to initialize the hardware in >> drivers/net/dsa/bcm_sf2.c > Do you mean this?: > core_writel(priv, reg, CORE_STS_OVERRIDE_GMIIP_PORT(port)); > Maybe just moving the HW initialization bits to some init func > will be a quick fix? Well, the problem with that is that to know how we should be configurin= g the hardware in the adjust_link function, we need to run the link_updat= e function first. By default, there is no auto-negotiation on these fixed links at all, so we cannot rely on any value being programmed other tha= n those specified in DT. >=20 >> for this to work, after that, the hardware >> reflects the fixed link parameters we configured, and we feed the >> fixed_phy_status information from the hardware directly. >> >> >From there I see two different ways to fix this: >> >> - we ignore the fixed_phy_update_regs return value in fixed_phy_add(= ), >> but that will make us avoid doing verification on the speed, which i= s >> not so great, but is essentially what your patch does anyway > No, it does not. All it does is to allow no speed _when link is down_= , > which is IMHO a very logical fix. The speed checks for the link-up > case are all still there. >=20 >> - we update the use of the fixed PHY link_update in drivers using it > IMHO just 2 drivers: bcmii.c and bcm_sf2.c, and the change > is likely trivial, although of course I am not sure in details. The changes are not trivial, it took a while to get that logic done correctly, and this would increase the number of patches to backport to -stable, which is not ideal. >=20 >> and >> convert them to use fixed_phy_update_state instead, which can take s= ome >> time and effort to convert > Maybe just move the initialization bits out of the link_update > callback, but still use the callback for now? Should be simple, no? Let me see if I have a smart idea other the weekend on how to do this. --=20 =46lorian