From: schwab@suse.de (Andreas Schwab) Date: Mon, 19 Nov 2018 16:13:10 +0100 Subject: [PATCH net-next v3 1/6] net: phy: mscc: migrate to phy_select/restore_page functions In-Reply-To: <20181119151057.GC26852@lunn.ch> (Andrew Lunn's message of "Mon, 19 Nov 2018 16:10:57 +0100") References: <20181008100728.24959-1-quentin.schulz@bootlin.com> <20181008100728.24959-2-quentin.schulz@bootlin.com> <20181119151057.GC26852@lunn.ch> Message-ID: To: linux-riscv@lists.infradead.org List-Id: linux-riscv.lists.infradead.org On Nov 19 2018, Andrew Lunn wrote: > On Mon, Nov 19, 2018 at 03:57:17PM +0100, Andreas Schwab wrote: >> On Okt 08 2018, Quentin Schulz wrote: >> >> > The Microsemi PHYs have multiple banks of registers (called pages). >> > Registers can only be accessed from one page, if we need a register from >> > another page, we need to switch the page and the registers of all other >> > pages are not accessible anymore. >> > >> > Basically, to read register 5 from page 0, 1, 2, etc., you do the same >> > phy_read(phydev, 5); but you need to set the desired page beforehand. >> > >> > In order to guarantee that two concurrent functions do not change the >> > page, we need to do some locking per page. This can be achieved with the >> > use of phy_select_page and phy_restore_page functions but phy_write/read >> > calls in-between those two functions shall be replaced by their >> > lock-free alternative __phy_write/read. >> > >> > Let's migrate this driver to those functions. >> >> This has some serious locking problem. > > Hi Andreas > > Could you be more specific. Are you getting a deadlock? A WARN_ON? See the stack trace. That's where it hangs. Andreas. -- Andreas Schwab, SUSE Labs, schwab at suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."