From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from down.free-electrons.com ([37.187.137.238] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Zvu7B-0005uQ-6M for linux-mtd@lists.infradead.org; Mon, 09 Nov 2015 21:36:37 +0000 Date: Mon, 9 Nov 2015 22:36:13 +0100 From: Boris Brezillon To: Brian Norris Cc: "Andrew E. Mileski" , linux-mtd , Scott Branden Subject: Re: Hang on reboot in nand_get_device() Message-ID: <20151109223613.1e83b256@bbrezillon> In-Reply-To: <20151109215508.7b14f5f3@bbrezillon> References: <55958F4C.1020002@isoar.ca> <20151106180052.GE12143@google.com> <20151106195903.0d55d819@bbrezillon> <20151109194651.GI12143@google.com> <20151109215508.7b14f5f3@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi again, Just want to add that this discussion shouldn't prevent your fix from being applied. The main reason I'm arguing here is because I want to understand the rationale behind the current handling of FL_PM_SUSPENDED and FL_SHUTDOWN. On Mon, 9 Nov 2015 21:55:08 +0100 Boris Brezillon wrote: > > > > > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > > > index ceb68ca..812b8b1 100644 > > > --- a/drivers/mtd/nand/nand_base.c > > > +++ b/drivers/mtd/nand/nand_base.c > > > @@ -830,6 +830,20 @@ nand_get_device(struct mtd_info *mtd, int new_state) > > > retry: > > > spin_lock(lock); > > > > > > + /* putting the NAND chip in shutdown state should always succeed. */ > > > + if (new_state == FL_SHUTDOWN) { > > > + /* > > > + * release the controller if the chip put in shutdown state > > > + * is the current active device. > > > + */ > > > + if (chip->controller->active == chip) > > > + chip->controller->active = NULL; > > > + > > > + chip->state = new_state; > > > + spin_unlock(lock); > > > + return 0; > > > + } > > > + > > > /* Hardware controller shared among independent devices */ > > > if (!chip->controller->active) > > > chip->controller->active = chip; > > > > > > > This looks a lot more subtle and potentially wrong. What exactly is the > > rationale here? It appears you're kind of unlocking the controller (any > > other flash on the same controller can still go ahead) but at the same > > time forcing no further users of this particular flash. It's even worst: I'm not waiting for the chip to become ready, so I'm potentially re-introducing the bug Scott was trying to solve with his reboot notifier. -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com