Messages in this thread | | | Date | Wed, 28 Jan 2015 12:34:59 -0500 | From | Murali Karicheri <> | Subject | Re: [PATCH v4 3/6] of: fix size when dma-range is not used |
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On 01/28/2015 10:45 AM, Rob Herring wrote: > On Wed, Jan 28, 2015 at 5:05 AM, Catalin Marinas > <catalin.marinas@arm.com> wrote: >> 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<joro@8bytes.org> >>>>> Cc: Grant Likely<grant.likely@linaro.org> >>>>> Cc: Rob Herring<robh+dt@kernel.org> >>>>> Cc: Bjorn Helgaas<bhelgaas@google.com> >>>>> Cc: Will Deacon<will.deacon@arm.com> >>>>> Cc: Russell King<linux@arm.linux.org.uk> >>>>> Cc: Arnd Bergmann<arnd@arndb.de> >>>>> Cc: Suravee Suthikulpanit<Suravee.Suthikulpanit@amd.com> >>>>> >>>>> Signed-off-by: Murali Karicheri<m-karicheri2@ti.com> >>>>> --- >>>>> 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; > > Are we assuming dma_addr, paddr and size are not touched on error? If > so, we can get rid of this clause entirely. Checking the code for of_dma_get_range() I see paddr is modified on error case, but is used only for success case in this function. dma_addr and size are not modified. So setting dma_addr and offset to zero before hand like size might work as below
dma_addr = offset = 0; size = 1ULL << 32;
ret = of_dma_get_range(dev->of_node,&dma_addr,&paddr,&size); if (!ret) { offset = PFN_DOWN(paddr - dma_addr); }
.. rest of the code.
Murali
> >> } 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; > > As I mentioned, I think power of 2 is too restrictive (from a DT > perspective even though the kernel may require a power of 2 here for > the mask). Just checking bit0 set should be enough. > > Also, we need a WARN here so DTs get fixed. > >> + >> + /* >> + * 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
-- Murali Karicheri Linux Kernel, Texas Instruments
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