Messages in this thread | | | Date | Tue, 27 Jan 2015 10:44:45 -0500 | From | Murali Karicheri <> | Subject | Re: [PATCH v4 3/6] of: fix size when dma-range is not used |
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On 01/27/2015 06:27 AM, Robin Murphy wrote: > Hi Murali, > > 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 > Robin,
I think this is better. I will wait for some more time for anyone to respond and re-send my patch with this change.
Thanks Murali > > Robin. > >> dev->dma_pfn_offset = offset; >> >> coherent = of_dma_is_coherent(np); >> > >
-- Murali Karicheri Linux Kernel, Texas Instruments
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