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Message-ID: <CAPv3WKeXtwJRPSaERzo+so+_ZAPSNk5RjxzE+N7u-uNUTMaeKA@mail.gmail.com> Date: Thu, 28 Jul 2022 08:52:04 +0200 From: Marcin Wojtas <mw@...ihalf.com> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: Vladimir Oltean <olteanv@...il.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, ACPI Devel Maling List <linux-acpi@...r.kernel.org>, netdev <netdev@...r.kernel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Sean Wang <sean.wang@...iatek.com>, Landen Chao <Landen.Chao@...iatek.com>, Linus Walleij <linus.walleij@...aro.org>, Andrew Lunn <andrew@...n.ch>, Vivien Didelot <vivien.didelot@...il.com>, Florian Fainelli <f.fainelli@...il.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Russell King - ARM Linux <linux@...linux.org.uk>, Heiner Kallweit <hkallweit1@...il.com>, Grzegorz Bernacki <gjb@...ihalf.com>, Grzegorz Jaszczyk <jaz@...ihalf.com>, Tomasz Nowicki <tn@...ihalf.com>, Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@....com>, "upstream@...ihalf.com" <upstream@...ihalf.com> Subject: Re: [net-next: PATCH v3 6/8] net: core: switch to fwnode_find_net_device_by_node() śr., 27 lip 2022 o 23:15 Andy Shevchenko <andy.shevchenko@...il.com> napisał(a): > > > > On Wednesday, July 27, 2022, Marcin Wojtas <mw@...ihalf.com> wrote: >> >> śr., 27 lip 2022 o 18:38 Vladimir Oltean <olteanv@...il.com> napisał(a): >> > >> > On Wed, Jul 27, 2022 at 05:18:16PM +0200, Marcin Wojtas wrote: >> > > Do you mean a situation analogous to what I addressed in: >> > > [net-next: PATCH v3 4/8] net: mvpp2: initialize port fwnode pointer >> > > ? >> > >> > Not sure if "analogous" is the right word. My estimation is that the >> > overwhelmingly vast majority of DSA masters can be found by DSA simply >> > due to the SET_NETDEV_DEV() call that the Ethernet drivers need to make >> > anyway. I see that mvpp2 also needed commit c4053ef32208 ("net: mvpp2: >> > initialize port of_node pointer"), but that isn't needed in general, and >> > I can't tell you exactly why it is needed there, I don't know enough >> > about the mvpp2 driver. >> >> SET_NETDEV_DEV() fills net_device->dev.parent with &pdev->dev >> and in most cases it is sufficient apparently it is sufficient for >> fwnode_find_parent_dev_match (at least tests with mvneta case proves >> it's fine). >> >> We have some corner cases though: >> * mvpp2 -> single controller can handle up to 3 net_devices and >> therefore we need device_set_node() to make this work. I think dpaa2 >> is a similar case >> * PCIE drivers with extra DT description (I think that's the case of enetc). >> >> > >> > > I found indeed a couple of drivers that may require a similar change >> > > (e.g. dpaa2). >> > >> > There I can tell you why the dpaa2-mac code mangles with net_dev->dev.of_node, >> > but I'd rather not go into an explanation that essentially doesn't matter. >> > The point is that you'd be mistaken to think that only the drivers which >> > touch the net device's ->dev->of_node are the ones that need updating >> > for your series to not cause regressions. >> >> As above - SET_NETDEV_DEV() should be fine in most cases, but we can >> never be 100% sure untils it's verified. >> >> > >> > > IMO we have 2 options: >> > > - update these drivers >> > > - add some kind of fallback? If yes, I am wondering about an elegant >> > > solution - maybe add an extra check inside >> > > fwnode_find_parent_dev_match? >> > > >> > > What would you suggest? >> > >> > Fixing fwnode_find_parent_dev_match(), of course. > > > > Fixing how?! > > >> >> >> This change broke DSA >> > on my LS1028A system (master in drivers/net/ethernet/freescale/enetc/) >> > and LS1021A (master in drivers/net/ethernet/freescale/gianfar.c). >> >> Can you please check applying following diff: >> >> --- a/drivers/base/property.c >> +++ b/drivers/base/property.c >> @@ -695,20 +695,22 @@ EXPORT_SYMBOL_GPL(fwnode_get_nth_parent); >> * The routine can be used e.g. as a callback for class_find_device(). >> * >> * Returns: %1 - match is found >> * %0 - match not found >> */ >> int fwnode_find_parent_dev_match(struct device *dev, const void *data) >> { >> for (; dev; dev = dev->parent) { >> if (device_match_fwnode(dev, data)) >> return 1; >> + else if (device_match_of_node(dev, to_of_node(data)) >> + return 1; >> } >> > > This adds a piece of dead code. device_match_fwnode() covers this already. > Yes, indeed. After recent update, I think we can assume the current implementation of fwnode_find_parent_dev_match should work fine with all existing cases. Thank you for all remarks and comments, I'll address them in v4 later today. Best regards, Marcin
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