Hi Tomasz,
   Thanks very much for your review. please help check below.
The others I will fix in the next version.

Hi Robin,
   There are some place I would like you can have a look and give me
some suggestion.

On Wed, 2015-03-11 at 19:53 +0900, Tomasz Figa wrote:

Hi,

Please find next part of my comments inline.

On Fri, Mar 6, 2015 at 7:48 PM,  [off-list ref] wrote:

[snip]

quoted

+/*
+ * pimudev is a global var for dma_alloc_coherent.
+ * It is not accepatable, we will delete it if "domain_alloc" is enabled

It looks like we indeed need to use dma_alloc_coherent() and we don't
have a good way to pass the device pointer to domain_init callback.

If you don't expect SoCs in the nearest future to have multiple M4U
blocks, then I guess this global variable could stay, after changing
the comment into an explanation why it's correct. Also it should be
moved to the top of the file, below #include directives, as this is
where usually global variables are located.

@Robin,
     We have merged this patch[0] in order to delete the global var, But
it seems that your patch of "arm64:IOMMU" isn't based on it right row.
it will build fail.

[0]:http://lists.linuxfoundation.org/pipermail/iommu/2015-January/011939.html

quoted

+ */
+static struct device *pimudev;
+

[snip]

quoted

+
+static int mtk_iommu_attach_device(struct iommu_domain *domain,
+                                  struct device *dev)
+{
+       unsigned long flags;
+       struct mtk_iommu_domain *priv = domain->priv;
+       struct mtk_iommu_info *piommu = priv->piommuinfo;
+       struct of_phandle_args out_args = {0};
+       struct device *imudev;
+       unsigned int i = 0;
+
+       if (!piommu)

Could you explain when this can happen?

	If we call arch_setup_dma_ops to create a iommu domain,
it will enter iommu_dma_attach_device, then enter here. At that time, we
don't add the private data to this "struct iommu_domain *".
@Robin, Could this be improved?

quoted

+               goto imudev;

return 0;

quoted

+       else

No else needed.

quoted

+               imudev = piommu->dev;
+
+       spin_lock_irqsave(&priv->portlock, flags);

What is protected by this spinlock?

	We will write a register of the local arbiter while config port. If
some modules are in the same local arbiter, it may be overwrite. so I
add it here.

quoted

+
+       while (!of_parse_phandle_with_args(dev->of_node, "iommus",
+                                          "#iommu-cells", i, &out_args)) {
+               if (1 == out_args.args_count) {

Can we be sure that this is actually referring to our IOMMU?

Maybe this should be rewritten to

if (out_args.np != imudev->of_node)
        continue;
if (out_args.args_count != 1) {
        dev_err(imudev, "invalid #iommu-cells property for IOMMU %s\n",

}

quoted

+                       unsigned int portid = out_args.args[0];
+
+                       dev_dbg(dev, "iommu add port:%d\n", portid);

imudev should be used here instead of dev.

quoted

+
+                       mtk_iommu_config_port(piommu, portid);
+
+                       if (i == 0)
+                               dev->archdata.dma_ops =
+                                       piommu->dev->archdata.dma_ops;

Shouldn't this be set automatically by IOMMU or DMA mapping core?

@Robin, 
     In the original "arm_iommu_attach_device" of arm/mm, it will call
set_dma_ops to add iommu_ops for each iommu device.
But iommu_dma_attach_device don't help this, so I have to add it here.
Could this be improved?

quoted

+               }
+               i++;
+       }
+
+       spin_unlock_irqrestore(&priv->portlock, flags);
+
+imudev:
+       return 0;
+}
+
+static void mtk_iommu_detach_device(struct iommu_domain *domain,
+                                   struct device *dev)
+{

No hardware (de)configuration or clean-up necessary?

I will add it. Actually we design like this:If a device have attached to
iommu domain, it won't detach from it.

quoted

+}
+

[snip]

quoted

+
+       piommu->protect_va = devm_kmalloc(piommu->dev, MTK_PROTECT_PA_ALIGN*2,

style: Operators like * should have space on both sides.

quoted

+                                         GFP_KERNEL);

Shouldn't dma_alloc_coherent() be used for this?

     We don't care the data in it. I think they are the same. Could you
help tell me why dma_alloc_coherent may be better.

quoted

+       if (!piommu->protect_va)
+               goto protect_err;

Please return -ENOMEM here directly, as there is nothing to clean up
in this case.

[snip]

quoted

+               dev_err(piommu->dev, "IRQ request %d failed\n",
+                       piommu->irq);
+               goto hw_err;
+       }
+
+       iommu_set_fault_handler(domain, mtk_iommu_fault_handler, piommu);

I don't see any other drivers doing this. Isn't this for upper layers,
so that they can set their own generic fault handlers?

     I think that this function is related with the iommu domain, we
have only one multimedia iommu domain. so I add it after the iommu
domain are created.

quoted

+
+       dev_set_drvdata(piommu->dev, piommu);

This should be set before allowing the interrupt to fire. In other
words, the driver should be fully set up at the time of enabling the
IRQ.

quoted

+
+       return 0;

style: Missing blank line.

quoted

+hw_err:
+       arch_teardown_dma_ops(piommu->dev);
+pte_err:
+       kmem_cache_destroy(piommu->m4u_pte_kmem);
+protect_err:
+       dev_err(piommu->dev, "probe error\n");

Please replace this with specific messages for all errors (in case the
called function doesn't already print one like kmalloc and friends).

quoted

+       return 0;

Returning 0, which means success, doesn't look like a good idea for
signalling a failure. Please return the correct error code as received
from function that errors out if possible.

End of part 3.

Best regards,
Tomasz