From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id EA14DDE072 for ; Tue, 14 Oct 2008 05:10:03 +1100 (EST) Message-Id: <209E575D-DDE2-406A-82DE-2DD445046C02@kernel.crashing.org> From: Kumar Gala To: Josh Boyer In-Reply-To: <20081013154127.GA27124@yoda.jdub.homelinux.org> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Mime-Version: 1.0 (Apple Message framework v929.2) Subject: Re: [PATCH V2 4/4] POWERPC: Merge 32 and 64-bit dma code Date: Mon, 13 Oct 2008 13:06:36 -0500 References: <1220900995-11928-5-git-send-email-becky.bruce@freescale.com> <1221251686-5567-1-git-send-email-becky.bruce@freescale.com> <20081013144904.GB18363@yoda.jdub.homelinux.org> <20081013154127.GA27124@yoda.jdub.homelinux.org> Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Oct 13, 2008, at 10:41 AM, Josh Boyer wrote: > On Mon, Oct 13, 2008 at 10:49:04AM -0400, Josh Boyer wrote: >> On Fri, Sep 12, 2008 at 03:34:46PM -0500, Becky Bruce wrote: >>> We essentially adopt the 64-bit dma code, with some changes to >>> support >>> 32-bit systems, including HIGHMEM. dma functions on 32-bit are now >>> invoked via accessor functions which call the correct op for a >>> device based >>> on archdata dma_ops. If there is no archdata dma_ops, this defaults >>> to dma_direct_ops. >>> >>> In addition, the dma_map/unmap_page functions are added to dma_ops >>> because we can't just fall back on map/unmap_single when HIGHMEM is >>> enabled. In the case of dma_direct_*, we stop using map/unmap_single >>> and just use the page version - this saves a lot of ugly >>> ifdeffing. We leave map/unmap_single in the dma_ops definition, >>> though, because they are needed by the iommu code, which does not >>> implement map/unmap_page. Ideally, going forward, we will >>> completely >>> eliminate map/unmap_single and just have map/unmap_page, if it's >>> workable for 64-bit. >>> >>> Signed-off-by: Becky Bruce >> >> While doing a buildall this morning, I notice chrp32_defconfig fails >> to build with: >> >> drivers/built-in.o: In function `hard_dma_setup': >> floppy.c:(.text+0x6e40e): undefined reference to `isa_bridge_pcidev' >> floppy.c:(.text+0x6e412): undefined reference to `isa_bridge_pcidev' >> floppy.c:(.text+0x6e53e): undefined reference to `isa_bridge_pcidev' >> floppy.c:(.text+0x6e546): undefined reference to `isa_bridge_pcidev' >> floppy.c:(.text+0x6e54a): undefined reference to `isa_bridge_pcidev' >> make[1]: *** [.tmp_vmlinux1] Error 1 >> >> (the hard_dma_setup thing is in arch/powerpc/include/asm/floppy.h). >> >> I did a git bisect and it pointed at this commit as causing the build >> to fail. Why, I have no idea. > > Ok, I was annoyed enough to look at why. > > Basically, before this patch pci_map_single on 32-bit PPC seemed to > be compiled down to __dma_sync(ptr, size, direction); and the "dev" > parameter to the function was never actually used. The compiler > seems to have optimized this out entirely, so we don't get the odd > link reference to isa_bridge_pcidev at all. (Neither pci_map_single > or isa_bridge_pcidev are present in the vmlinux at all). > > With the patch, the compiler doesn't do this code elimination > because pci_map_single boils down to dma_map_page, which calls > get_dma_direct_offset with the "dev" parameter. So since it is > still used, the compiler can't eliminate it and hence FAIL. > > I have no patch for this at the moment. Someone should look at > it more closely, because this is causing the 5 chrp32_defconfig > users to weep. Isn't this the type of regression we should fix post -rc1 :) - k