Messages in this thread | | | Date | Wed, 11 Mar 2020 08:59:27 +0100 | From | Michael Walle <> | Subject | Re: [RFC PATCH] mfd: mfd-core: inherit only valid dma_masks/flags from parent |
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Am 2020-03-11 07:18, schrieb Christoph Hellwig: > On Wed, Mar 11, 2020 at 12:09:35AM +0100, Michael Walle wrote: >> Only copy the dma_masks and flags from the parent device, if the >> parent >> has a valid dma_mask/flags. Commit cdfee5623290 ("driver core: >> initialize a default DMA mask for platform device") initialize the DMA >> masks of a platform device. But if the parent doesn't have a dma_mask >> set, for example if it's an I2C device, the dma_mask of the child >> platform device will be set to zero again. Which leads to many "DMA >> mask >> not set" warnings, if the MFD cell has the of_compatible property set. >> >> [ 1.877937] sl28cpld-pwm sl28cpld-pwm: DMA mask not set >> [ 1.883282] sl28cpld-pwm sl28cpld-pwm.0: DMA mask not set >> [ 1.888795] sl28cpld-gpio sl28cpld-gpio: DMA mask not set >> >> Thus a MFD child should just inherit valid dma_masks and keep the >> platform default otherwise. >> >> Cc: Christoph Hellwig <hch@lst.de> >> Cc: Rob Herring <robh@kernel.org> >> Cc: Robin Murphy <robin.murphy@arm.com> >> Cc: Russell King <linux@armlinux.org.uk> >> Signed-off-by: Michael Walle <michael@walle.cc> >> --- >> >> Hi, >> >> I don't know if that is the correct way of handling things. Maybe I'm >> also doing something wrong in my driver, I had a look at other I2C MFD >> drivers but couldn't find a clue why they shouldn't have the same >> problem. >> >> There was also a thread [1] about this topic, but there seems to be no >> conclusion. >> >> [1] https://www.spinics.net/lists/linux-renesas-soc/msg31581.html >> >> drivers/mfd/mfd-core.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c >> index b9eb8f40c073..5d8ea5e8e93c 100644 >> --- a/drivers/mfd/mfd-core.c >> +++ b/drivers/mfd/mfd-core.c >> @@ -139,9 +139,12 @@ static int mfd_add_device(struct device *parent, >> int id, >> >> pdev->dev.parent = parent; >> pdev->dev.type = &mfd_dev_type; >> - pdev->dev.dma_mask = parent->dma_mask; >> - pdev->dev.dma_parms = parent->dma_parms; >> - pdev->dev.coherent_dma_mask = parent->coherent_dma_mask; >> + if (parent->dma_mask) >> + pdev->dev.dma_mask = parent->dma_mask; >> + if (parent->dma_parms) >> + pdev->dev.dma_parms = parent->dma_parms; > > Both of these are pointers, and we can't just share them. You need > to allocate storage for them and the allocate the values over.
So they were alreay copied wrong before this patch? If so, should there be a fixes patch for it? The commit who introduced the copy dates back to 2013: b018e1361bad3 mfd: core: Copy DMA mask and params from parent
-michael
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