Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751189AbVLUTdG (ORCPT ); Wed, 21 Dec 2005 14:33:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751192AbVLUTdF (ORCPT ); Wed, 21 Dec 2005 14:33:05 -0500 Received: from omx1-ext.sgi.com ([192.48.179.11]:25557 "EHLO omx1.americas.sgi.com") by vger.kernel.org with ESMTP id S1751189AbVLUTdE (ORCPT ); Wed, 21 Dec 2005 14:33:04 -0500 Date: Wed, 21 Dec 2005 13:33:00 -0600 From: Mark Maule To: Matthew Wilcox Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Tony Luck Subject: Re: [PATCH 2/4] msi vector targeting abstractions Message-ID: <20051221193300.GK9920@sgi.com> References: <20051221184337.5003.85653.32527@attica.americas.sgi.com> <20051221184348.5003.7540.53186@attica.americas.sgi.com> <20051221190558.GD2361@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051221190558.GD2361@parisc-linux.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2900 Lines: 92 On Wed, Dec 21, 2005 at 12:05:58PM -0700, Matthew Wilcox wrote: > On Wed, Dec 21, 2005 at 12:42:41PM -0600, Mark Maule wrote: > > > @@ -108,28 +125,38 @@ > > if (!(pos = pci_find_capability(entry->dev, PCI_CAP_ID_MSI))) > > return; > > > > + pci_read_config_dword(entry->dev, msi_upper_address_reg(pos), > > + &address_hi); > > pci_read_config_dword(entry->dev, msi_lower_address_reg(pos), > > - &address.lo_address.value); > > - address.lo_address.value &= MSI_ADDRESS_DEST_ID_MASK; > > - address.lo_address.value |= (cpu_physical_id(dest_cpu) << > > - MSI_TARGET_CPU_SHIFT); > > - entry->msi_attrib.current_cpu = cpu_physical_id(dest_cpu); > > + &address_lo); > > + > > + msi_callouts.msi_target(vector, dest_cpu, > > + &address_hi, &address_lo); > > + > > + pci_write_config_dword(entry->dev, msi_upper_address_reg(pos), > > + address_hi); > > pci_write_config_dword(entry->dev, msi_lower_address_reg(pos), > > - address.lo_address.value); > > + address_lo); > > But actually, I don't understand why you don't just pass a msg_address > pointer to msi_target instead. Mainly I did it this way 'cause msg_address seems to be geared toward specific hw (apic?). In the case of altix interrupt hw, we don't know about dest_mode et. al., but only care about the raw address. I think this style makes it clearer that the core code should only be using opaque data when interacting with the platform hooks and the MSI registers. > > (last two points apply throughtout this patch) > > > > > + (*msi_callouts.msi_teardown)(vector); > > + > > Yuck. There's a reason C allows you to call through function pointers as if > they were functions. My bad ... I used the alternate style elsewhere, just botched this one up. > > > +int > > +msi_register_callouts(struct msi_callouts *co) > > +{ > > + msi_callouts = *co; /* structure copy */ > > + return 0; > > Why do it this way instead of having a pointer to a struct? Are you suggesting just have: struct msi_callouts *msi_callouts = (some default value or NULL) and then having each platform just assign msi_callouts in their msi_arch_init? Doesn't matter to me either way ... I thought having an interface to set the callouts was cleaner. > > > -struct msg_data { > > +union msg_data { > > + struct { > > How about leaving struct msg_data alone and adding > > union good_name { > struct msg_data; > u32 value; > } > > Or possibly struct msg_data should just be deleted and we should use > shift/mask to access the contents of it. ISTR GCC handled that much > better. Christoph had similiar comments. Will put some thought into it. Mark - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/