From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755553AbaLVRqt (ORCPT ); Mon, 22 Dec 2014 12:46:49 -0500 Received: from bear.ext.ti.com ([192.94.94.41]:54308 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754621AbaLVRqr (ORCPT ); Mon, 22 Dec 2014 12:46:47 -0500 Message-ID: <549858E4.4050500@ti.com> Date: Mon, 22 Dec 2014 12:46:12 -0500 From: Murali Karicheri User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Arnd Bergmann CC: , , , , , , , Subject: Re: [RFC v1 PATCH 1/2] of/pci: add of_pci_dma_configure() update dma configuration References: <1418940425-2017-1-git-send-email-m-karicheri2@ti.com> <1418940425-2017-2-git-send-email-m-karicheri2@ti.com> <21520995.3ITgVmVTeV@wuerfel> In-Reply-To: <21520995.3ITgVmVTeV@wuerfel> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/18/2014 05:29 PM, Arnd Bergmann wrote: > On Thursday 18 December 2014 17:07:04 Murali Karicheri wrote: >> Add of_pci_dma_configure() to allow updating the dma configuration >> of the pci device using the configuration from the parent of >> the root bridge device. >> >> Signed-off-by: Murali Karicheri > > Much better! > > There is one detail that we should get right from the start here, > which is currently wrong in the platform device code, but I have so > far not dared change it: > >> + /* >> + * Set default dma-mask to 32 bit. Drivers are expected to setup >> + * the correct supported dma_mask. >> + */ >> + dev->coherent_dma_mask = DMA_BIT_MASK(32); > > The 32-bit mask is indeed correct as the default for almost all cases, > and we must not set it larger than DMA_BIT_MASK(32). There is one > corner case though, which happens on some shmobile machines that have > a 31-bit mask on the PCI host, and I think we should use that as the > default. > >> + /* >> + * Set it to coherent_dma_mask by default if the architecture >> + * code has not set it. >> + */ >> + if (!dev->dma_mask) >> + dev->dma_mask =&dev->coherent_dma_mask; >> + >> + ret = of_dma_get_range(parent_np,&dma_addr,&paddr,&size); >> + if (ret< 0) { >> + dma_addr = offset = 0; >> + size = dev->coherent_dma_mask; > > Can you check one thing here? I believe the size argument as returned > from of_dma_get_range is inclusive (e.g. 0x100000000), while the coherent > mask by definition is exlusive (e.g. 0xffffffff), so the size needs to > be adapted here. I haven't checked all the code here though, so I may > be wrong. size returned by of_dma_get_range() is inclusive as you indicated. Fromt the grep of dma-ranges in arch/arm/boot/dts, I see arch/arm/boot/dts/keystone.dtsi: dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>; arch/arm/boot/dts/keystone.dtsi: dma-ranges; arch/arm/boot/dts/r8a7790.dtsi: dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0 0x80000000 arch/arm/boot/dts/integratorap.dts: dma-ranges = <0x80000000 0x0 0x80000000>; arch/arm/boot/dts/r8a7791.dtsi: dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0 0x80000000 So I guess I need to change the code to >> + ret = of_dma_get_range(parent_np,&dma_addr,&paddr,&size); >> + if (ret< 0) { >> + dma_addr = offset = 0; >> + size = dev->coherent_dma_mask + 1; > >> + } else { >> + offset = PFN_DOWN(paddr - dma_addr); >> + dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset); >> + } >> + dev->dma_pfn_offset = offset; >> + >> + coherent = of_dma_is_coherent(parent_np); >> + dev_dbg(dev, "device is%sdma coherent\n", >> + coherent ? " " : " not "); >> + >> + arch_setup_dma_ops(dev, dma_addr, size, NULL, coherent); > > Basically, I would use limit the size argument we pass into > arch_setup_dma_ops to the minimum of 'size' and 'dma_mask' here, > after converting into the same format. We should make sure we do the > same thing for platform_device as well, so it might be better to do > it inside of arch_setup_dma_ops instead. Do you think following changes will work? +++ b/arch/arm/mm/dma-mapping.c @@ -2052,9 +2052,10 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, struct iommu_ops *iommu, bool coherent) { struct dma_map_ops *dma_ops; + u64 temp_size = min((*(dev->dma_mask) + 1), size); dev->archdata.dma_coherent = coherent; - if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu)) + if (arm_setup_iommu_dma_ops(dev, dma_base, temp_size, iommu)) If you agree, I will post v1 of the patch with these updates. Let me know. I did some basic tests on Keystone with these changes and it works fine. Murali > > Arnd -- Murali Karicheri Linux Kernel, Texas Instruments