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Message-ID: <41668eff-271c-1c4c-7665-3bf0faa74669@codeaurora.org>
Date: Tue, 23 May 2017 02:26:10 -0400
From: Nate Watterson <nwatters@...eaurora.org>
To: Sricharan R <sricharan@...eaurora.org>, robin.murphy@....com,
will.deacon@....com, joro@...tes.org, lorenzo.pieralisi@....com,
iommu@...ts.linux-foundation.org,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, m.szyprowski@...sung.com,
bhelgaas@...gle.com, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, tn@...ihalf.com, hanjun.guo@...aro.org,
okaya@...eaurora.org, robh+dt@...nel.org, frowand.list@...il.com,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
sudeep.holla@....com, rjw@...ysocki.net, lenb@...nel.org,
catalin.marinas@....com, arnd@...db.de, linux-arch@...r.kernel.org,
gregkh@...uxfoundation.org
Subject: Re: [PATCH V11 08/11] drivers: acpi: Handle IOMMU lookup failure with
deferred probing or error
Hi Sricharan,
On 4/10/2017 7:21 AM, Sricharan R wrote:
> This is an equivalent to the DT's handling of the iommu master's probe
> with deferred probing when the corrsponding iommu is not probed yet.
> The lack of a registered IOMMU can be caused by the lack of a driver for
> the IOMMU, the IOMMU device probe not having been performed yet, having
> been deferred, or having failed.
>
> The first case occurs when the firmware describes the bus master and
> IOMMU topology correctly but no device driver exists for the IOMMU yet
> or the device driver has not been compiled in. Return NULL, the caller
> will configure the device without an IOMMU.
>
> The second and third cases are handled by deferring the probe of the bus
> master device which will eventually get reprobed after the IOMMU.
>
> The last case is currently handled by deferring the probe of the bus
> master device as well. A mechanism to either configure the bus master
> device without an IOMMU or to fail the bus master device probe depending
> on whether the IOMMU is optional or mandatory would be a good
> enhancement.
>
> Tested-by: Hanjun Guo <hanjun.guo@...aro.org>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> [Lorenzo: Added fixes for dma_coherent_mask overflow, acpi_dma_configure
> called multiple times for same device]
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> ---
> drivers/acpi/arm64/iort.c | 33 ++++++++++++++++++++++++++++++++-
> drivers/acpi/scan.c | 11 ++++++++---
> drivers/base/dma-mapping.c | 2 +-
> include/acpi/acpi_bus.h | 2 +-
> include/linux/acpi.h | 7 +++++--
> 5 files changed, 47 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 3dd9ec3..e323ece 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -543,6 +543,14 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
> const struct iommu_ops *ops = NULL;
> int ret = -ENODEV;
> struct fwnode_handle *iort_fwnode;
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> +
> + /*
> + * If we already translated the fwspec there
> + * is nothing left to do, return the iommu_ops.
> + */
> + if (fwspec && fwspec->ops)
> + return fwspec->ops;
Is this logic strictly required? It breaks masters with multiple SIDs
as only the first SID is actually added to the master's fwspec.
>
> if (node) {
> iort_fwnode = iort_get_fwnode(node);
> @@ -550,8 +558,17 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
> return NULL;
>
> ops = iommu_ops_from_fwnode(iort_fwnode);
> + /*
> + * If the ops look-up fails, this means that either
> + * the SMMU drivers have not been probed yet or that
> + * the SMMU drivers are not built in the kernel;
> + * Depending on whether the SMMU drivers are built-in
> + * in the kernel or not, defer the IOMMU configuration
> + * or just abort it.
> + */
> if (!ops)
> - return NULL;
> + return iort_iommu_driver_enabled(node->type) ?
> + ERR_PTR(-EPROBE_DEFER) : NULL;
>
> ret = arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
> }
> @@ -625,12 +642,26 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
>
> while (parent) {
> ops = iort_iommu_xlate(dev, parent, streamid);
> + if (IS_ERR_OR_NULL(ops))
> + return ops;
>
> parent = iort_node_get_id(node, &streamid,
> IORT_IOMMU_TYPE, i++);
> }
> }
>
> + /*
> + * If we have reason to believe the IOMMU driver missed the initial
> + * add_device callback for dev, replay it to get things in order.
> + */
> + if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
> + dev->bus && !dev->iommu_group) {
> + int err = ops->add_device(dev);
> +
> + if (err)
> + ops = ERR_PTR(err);
> + }
> +
> return ops;
> }
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 1926918..2a513cc 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1373,20 +1373,25 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
> * @dev: The pointer to the device
> * @attr: device dma attributes
> */
> -void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
> +int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
> {
> const struct iommu_ops *iommu;
> + u64 size;
>
> iort_set_dma_mask(dev);
>
> iommu = iort_iommu_configure(dev);
> + if (IS_ERR(iommu))
> + return PTR_ERR(iommu);
>
> + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
> /*
> * Assume dma valid range starts at 0 and covers the whole
> * coherent_dma_mask.
> */
> - arch_setup_dma_ops(dev, 0, dev->coherent_dma_mask + 1, iommu,
> - attr == DEV_DMA_COHERENT);
> + arch_setup_dma_ops(dev, 0, size, iommu, attr == DEV_DMA_COHERENT);
> +
> + return 0;
> }
> EXPORT_SYMBOL_GPL(acpi_dma_configure);
>
> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
> index 82bd45c..755a2b5 100644
> --- a/drivers/base/dma-mapping.c
> +++ b/drivers/base/dma-mapping.c
> @@ -368,7 +368,7 @@ int dma_configure(struct device *dev)
> } else if (has_acpi_companion(dma_dev)) {
> attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode));
> if (attr != DEV_DMA_NOT_SUPPORTED)
> - acpi_dma_configure(dev, attr);
> + ret = acpi_dma_configure(dev, attr);
> }
>
> if (bridge)
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index ef0ae8a..2a9a5de 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -575,7 +575,7 @@ struct acpi_pci_root {
>
> bool acpi_dma_supported(struct acpi_device *adev);
> enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev);
> -void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr);
> +int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr);
> void acpi_dma_deconfigure(struct device *dev);
>
> struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 9b05886..79d06ef6 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -762,8 +762,11 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
> return DEV_DMA_NOT_SUPPORTED;
> }
>
> -static inline void acpi_dma_configure(struct device *dev,
> - enum dev_dma_attr attr) { }
> +static inline int acpi_dma_configure(struct device *dev,
> + enum dev_dma_attr attr)
> +{
> + return 0;
> +}
>
> static inline void acpi_dma_deconfigure(struct device *dev) { }
>
>
--
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