From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v4 3/6] of: fix size when dma-range is not used Date: Wed, 28 Jan 2015 11:05:23 +0000 Message-ID: <20150128110523.GC6646@e104818-lin.cambridge.arm.com> References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <1422052359-12384-4-git-send-email-m-karicheri2@ti.com> <54C77616.80301@arm.com> <54C7DF13.20402@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <54C7DF13.20402-l0cyMroinI0@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Murali Karicheri Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Arnd Bergmann , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Will Deacon , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Bjorn Helgaas , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Rob Herring , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On Tue, Jan 27, 2015 at 06:55:15PM +0000, Murali Karicheri wrote: > On 01/27/2015 06:27 AM, Robin Murphy wrote: > > On 23/01/15 22:32, Murali Karicheri wrote: > >> Fix the dma-range size when the DT attribute is missing. i.e set size to > >> dev->coherent_dma_mask + 1 instead of dev->coherent_dma_mask. To detect > >> overflow when mask is set to max of u64, add a check, log error and > >> return. > >> Some platform use mask format for size in DTS. So add a work around to > >> catch this and fix. > >> > >> Cc: Joerg Roedel > >> Cc: Grant Likely > >> Cc: Rob Herring > >> Cc: Bjorn Helgaas > >> Cc: Will Deacon > >> Cc: Russell King > >> Cc: Arnd Bergmann > >> Cc: Suravee Suthikulpanit > >> > >> Signed-off-by: Murali Karicheri > >> --- > >> drivers/of/device.c | 14 +++++++++++++- > >> 1 file changed, 13 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/of/device.c b/drivers/of/device.c > >> index 2de320d..0a5ff54 100644 > >> --- a/drivers/of/device.c > >> +++ b/drivers/of/device.c > >> @@ -105,12 +105,24 @@ void of_dma_configure(struct device *dev, struct > >> device_node *np) > >> ret = of_dma_get_range(np, &dma_addr, &paddr, &size); > >> if (ret < 0) { > >> dma_addr = offset = 0; > >> - size = dev->coherent_dma_mask; > >> + size = dev->coherent_dma_mask + 1; > >> } else { > >> offset = PFN_DOWN(paddr - dma_addr); > >> + /* > >> + * Add a work around to treat the size as mask + 1 in case > >> + * it is defined in DT as a mask. > >> + */ > >> + if (size & 1) > >> + size = size + 1; > >> dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); > >> } > >> > >> + /* if size is 0, we have an overflow of u64 */ > >> + if (!size) { > >> + dev_err(dev, "invalid size\n"); > >> + return; > >> + } > >> + > > > > This seems potentially fragile to dodgy DTs given that we might also be > > using size to make a mask later. Would it make sense to double-up a > > sanity check as mask-format detection? Something like: > > > > if is_power_of_2(size) > > // use size > > else if is_power_of_2(size + 1) > > // use size + 1 > > else > > // cry > > How about having the logic like this? > > ret = of_dma_get_range(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", offset); > } > > if (is_power_of_2(size + 1)) > size = size + 1; > else if (!is_power_of_2(size)) > { > dev_err(dev, "invalid size\n"); > return; > } In of_dma_configure(), we currently assume that the default coherent mask is 32-bit. In this thread: http://article.gmane.org/gmane.linux.kernel/1835096 we talked about setting the coherent mask based on size automatically. I'm not sure about the size but I think we can assume is 32-bit mask + 1 if it is not specified in the DT. Instead of just assuming a default mask, let's assume a default size and create the mask based on this (untested): diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 5b33c6a21807..9ff8d1286b44 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -170,10 +170,10 @@ static void of_dma_configure(struct device *dev) struct iommu_ops *iommu; /* - * Set default dma-mask to 32 bit. Drivers are expected to setup - * the correct supported dma_mask. + * Set default size to cover the 32-bit. Drivers are expected to setup + * the correct size and dma_mask. */ - dev->coherent_dma_mask = DMA_BIT_MASK(32); + size = 1ULL << 32; /* * Set it to coherent_dma_mask by default if the architecture @@ -185,13 +185,24 @@ static void of_dma_configure(struct device *dev) ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size); if (ret < 0) { dma_addr = offset = 0; - size = dev->coherent_dma_mask; } else { offset = PFN_DOWN(paddr - dma_addr); dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset); } dev->dma_pfn_offset = offset; + /* + * Workaround for DTs setting the size to a mask or 0. + */ + if (is_power_of_2(size + 1)) + size += 1; + + /* + * Coherent DMA masks larger than 32-bit must be explicitly set by the + * driver. + */ + dev->coherent_dma_mask = min(DMA_BIT_MASK(32), DMA_BIT_MASK(ilog2(size))); + coherent = of_dma_is_coherent(dev->of_node); dev_dbg(dev, "device is%sdma coherent\n", coherent ? " " : " not "); -- Catalin