From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH] libata: waits up to 10 microseconds for early irq problem Date: Tue, 28 Nov 2006 09:16:25 -0500 Message-ID: <456C44B9.2050300@rtr.ca> References: <200611180759.34622.t.powa@gmx.de> <20061118002357.564dbb9d.akpm@osdl.org> <455F790C.2030509@garzik.org> <456BDCAC.4060609@tw.ibm.com> <20061128102534.5a42c9b2@localhost.localdomain> <456C0F11.30301@gmail.com> <20061128104659.4ec91296@localhost.localdomain> <456C410C.9060604@pobox.com> <20061128141200.104facf3@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([64.26.128.89]:7686 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S935219AbWK1OQ1 (ORCPT ); Tue, 28 Nov 2006 09:16:27 -0500 In-Reply-To: <20061128141200.104facf3@localhost.localdomain> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cc: Mark Lord , Tejun Heo , albertl@mail.com, albertcc@tw.ibm.com, Jeff Garzik , Linux IDE , matthieu castet , Tobias Powalowski Alan wrote: > On Tue, 28 Nov 2006 09:00:44 -0500 > Mark Lord wrote: > >> Alan, I confess that I really don't understand this example (below). >> Can you try again, with something concrete enough for a rusty old >> IDE hacker to understand? > > The asynchronocity isn't at the IDE level - its at the PCI bus level. The > IRQ path between a PCI card and the CPU is not synchronous to I/O cycles. Yes, I know that much already. But how does that factor into the need for this particular patch, (apart from truly buggy drives which send the IRQ before clearing BUSY) ? The device driver won't do ANY I/O until it sees the IRQ, so things are synchronized already without needing to do an extra status poll in response to the IRQ. ??? Thanks