From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH][0/2] RTAS MSI From: Michael Ellerman To: Segher Boessenkool In-Reply-To: <802085A1-AA37-4787-A2D6-B619C6BE7AB4@kernel.crashing.org> References: <1154024154.29826.229.camel@goblue> <1154062599.21801.40.camel@localhost.localdomain> <802085A1-AA37-4787-A2D6-B619C6BE7AB4@kernel.crashing.org> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-z5EguXknhtAI47ABPy9N" Date: Wed, 09 Aug 2006 12:23:30 +1000 Message-Id: <1155090210.7087.4.camel@localhost.localdomain> Mime-Version: 1.0 Cc: Paul Mackerras , linuxppc-dev@ozlabs.org Reply-To: michael@ellerman.id.au List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-z5EguXknhtAI47ABPy9N Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Fri, 2006-07-28 at 20:43 +0200, Segher Boessenkool wrote: > >> The RTAS patch skips the intel-centric MSI layer and uses > >> pci_enable/disable_msi() calls directly. It does not correctly =20 > >> handle > >> multi-vector MSI either. > > > > Multi-vector MSIs aren't handled by the linux API anyway it seems (the > > doc says pci_enable_msi() only ever enables one MSI) so that's fine if > > you don't handle them :) The word on the street is that multivector =20 > > MSIs > > aren't useful, MSI-X are. >=20 > pci_enable_msi() should always enable exactly one or zero MSIs. Maybe > Jake's patch doesn't follow this rule, and that is what he alluded to? I was just re-reading this thread and this got me thinking. I think the current code does violate this rule if firmware has allocated more than one MSI to the device. In rtas_enable_msi() we ask firmware how many MSIs the device has been given (by firmware), we then return one to the driver, but leave any extras configured. So this might lead to the state where the card has been configured to use x MSIs, but we only tell the driver about 1 of them. I don't know enough PCI to grok if that's going to be a problem. cheers --=20 Michael Ellerman IBM OzLabs wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-z5EguXknhtAI47ABPy9N Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (GNU/Linux) iD8DBQBE2UchdSjSd0sB4dIRApVqAJ476v54IIao9hXH/1Z3KAgDcoRalwCeJgSU oJGbqy0VXuQ9oIjsBQH66dQ= =SSps -----END PGP SIGNATURE----- --=-z5EguXknhtAI47ABPy9N--