RE: [PATCH 1/3] iommu/fsl: Factor out PCI specific code.

-----Original Message-----
From: iommu-bounces@lists.linux-foundation.org [mailto:iommu-
bounces@lists.linux-foundation.org] On Behalf Of Bjorn Helgaas
Sent: Tuesday, October 15, 2013 5:46 AM
To: Sethi Varun-B16395
Cc: Yoder Stuart-B08248; linux-kernel@vger.kernel.org; iommu@lists.linux-
foundation.org; Bhushan Bharat-R65777; Wood Scott-B07421; linuxppc-
dev@lists.ozlabs.org
Subject: Re: [PATCH 1/3] iommu/fsl: Factor out PCI specific code.
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On Sun, Oct 13, 2013 at 02:02:32AM +0530, Varun Sethi wrote:

quoted

Factor out PCI specific code in the PAMU driver.

Signed-off-by: Varun Sethi <redacted>
---
 drivers/iommu/fsl_pamu_domain.c |   81 +++++++++++++++++++------------

--------

quoted

 1 file changed, 40 insertions(+), 41 deletions(-)

diff --git a/drivers/iommu/fsl_pamu_domain.c

b/drivers/iommu/fsl_pamu_domain.c index c857c30..e02e1de 100644

--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c

@@ -677,13 +677,9 @@ static int handle_attach_device(struct

fsl_dma_domain *dma_domain,

quoted

 	return ret;
 }

-static int fsl_pamu_attach_device(struct iommu_domain *domain,
-				  struct device *dev)
+static void check_for_pci_dma_device(struct device **dev)

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"check_for_pci_dma_device()" doesn't give a good clue about what the
function returns.  And why return something via a reference parameter
when you could return it directly?

[Sethi Varun-B16395] I will rename the function to get_dma_device and make =
it return a pointer.

=20

quoted

 {
-	struct fsl_dma_domain *dma_domain =3D domain->priv;
-	const u32 *liodn;
-	u32 liodn_cnt;
-	int len, ret =3D 0;
+#ifdef CONFIG_PCI
 	struct pci_dev *pdev =3D NULL;
 	struct pci_controller *pci_ctl;

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This is sort of a goofy looking function.  It would read much better as
something like this:
=20

[Sethi Varun-B16395] Will make the change.

      struct device *dma_dev =3D dev;
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  #ifdef CONFIG_PCI
      if (...) {
          dma_dev =3D ...;
      }
  #endif
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      return dma_dev;
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Does this need to care about reference counting when you return a pointer
to a different device?
=20

[Sethi Varun-B16395] Reference counting isn't required, as we are just obta=
ining the LIODN value from the PCI controller.

-Varun