From mboxrd@z Thu Jan 1 00:00:00 1970 From: b.brezillon@overkiz.com (boris brezillon) Date: Thu, 22 Aug 2013 15:24:14 +0200 Subject: [RFC PATCH] phylib: mdio: handle register/unregister/register sequence In-Reply-To: References: <1377174836-10569-1-git-send-email-b.brezillon@overkiz.com> <52160CAC.3040603@overkiz.com> Message-ID: <521610FE.7080807@overkiz.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 22/08/2013 15:15, Florian Fainelli wrote: > 2013/8/22 boris brezillon : >> Hello Florian, >> >> Thanks for your answer. >> >> >> On 22/08/2013 14:43, Florian Fainelli wrote: >>> Hello Boris, >>> >>> 2013/8/22 Boris BREZILLON : >>>> Hello, >>>> >>>> This patch is a proposal to support the register/unregister/register >>>> sequence on a given mdio bus. >>>> >>>> I use the register/unregister/register sequence to add a fallback when >>>> the >>>> of_mdiobus_register (this function calls mdiobus_register with phy_mask >>>> set to ~0) does not register any phy device (because the device tree does >>>> not define any phy). >>>> In this case I call mdiobus_unregister and then call mdiobus_register >>>> with >>>> a phy_mask set to 0 to trigger a full mdio bus scan. >>>> >>>> I'm not sure this is the right way to do it (this is why I added RFC in >>>> the >>>> subject). >>>> >>>> Could someone help me figuring out what I should use to implement my >>>> fallback ? >>>> >>>> 1) use the register/unregister/register sequence >>>> 2) reimplement the "for (i = 0; i < PHY_MAX_ADDR; i++)" mdiobus_scan loop >>> I think solution 2 is nicer, in that case, would it be enough in your >>> case to export a function called mdiobus_scan()? You could call at a >>> time you know PHY devices have a chance of having been probed? >> mdiobus_scan is already exported: >> struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr); >> >> This function scans the presence of a phy device at a given address. >> >> What I need is a loop which scan all the possible address on the given >> mdio bus: >> >> struct phy_device *mdiobus_full_scan(struct mii_bus *bus) >> { >> int i; >> for (i = 0; i < PHY_MAX_ADDR; i++) { >> if ((bus->phy_mask & (1 << i)) == 0) { >> struct phy_device *phydev; >> >> phydev = mdiobus_scan(bus, i); >> if (IS_ERR(phydev)) { >> err = PTR_ERR(phydev); >> goto error; >> } >> } >> } >> return 0; >> >> error: >> while (--i >= 0) { >> >> if (bus->phy_map[i]) >> device_unregister(&bus->phy_map[i]->dev); >> } >> } >> EXPORT_SYMBOL(mdiobus_full_scan); >> >> Since I am the only one who need this kind of functionnality right now, I'm >> not sure >> this is a good idea to export a new function. > A possible other use case for this full-scan is when you do not detect > a PHY connected to your MDIO bus, and that you did not register a > fixed PHY early enough for it to have been scanned by the fixed MDIO > bus emulation. In that case the driver may: > > - scan hardware MDIO bus > - do not find any PHY, register a fixed PHY > - trigger a fixed MDIO bus full-rescan > - attach to the discovered fixed PHY > > this is something currently done by the TI CPMAC driver in > drivers/net/ethernet/ti/cpmac.c (altough fixed_phy_add() is called > from platform code). > Okay, then we should consider this option. >> This behaviour may be implemented in the of_mdiobus_register function: >> when no dt phy node are found in the mdio bus dt node, we could launch a >> full >> scan. >> >> What do you think ? > There is an existing kind of "autoscan" feature in > drivers/of/of_mdio.c, starting with the second foreach_child_node() > loop, so maybe that specific part could be exported and would achieve > what you are looking for? It relies on the Ethernet PHY nodes to be > attached to the MDIO bus node, but I assume this is what ultimately > happens in your case as well? The second foreach_child_node loop only registers the dt phy nodes which does not define any reg property (automatic address asssignement ?). Indeed, what I need is a fallback when the device tree does not define any phy device (for old device tree backward compatibility).