From: andrew@lunn.ch (Andrew Lunn) Date: Mon, 19 Nov 2018 16:10:57 +0100 Subject: [PATCH net-next v3 1/6] net: phy: mscc: migrate to phy_select/restore_page functions In-Reply-To: References: <20181008100728.24959-1-quentin.schulz@bootlin.com> <20181008100728.24959-2-quentin.schulz@bootlin.com> Message-ID: <20181119151057.GC26852@lunn.ch> To: linux-riscv@lists.infradead.org List-Id: linux-riscv.lists.infradead.org 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? Thanks, Andrew