Re: [V4 PATCH 3/6] pci: Generic function for setting up PCI device DMA coherency

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Friday, May 15, 2015 04:23:11 PM Suravee Suthikulpanit wrote:
> This patch refactors of_pci_dma_configure() into a more generic
> pci_dma_configure(), which can be reused by non-OF code.
> Then, it adds support for setting up PCI device DMA coherency from
> ACPI _CCA object that should normally be specified in the DSDT node
> of its PCI host bridge..
> 
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: Catalin Marinas <catalin.marinas@arm.com>
> CC: Rob Herring <robh+dt@kernel.org>
> CC: Will Deacon <will.deacon@arm.com>
> CC: Rafael J. Wysocki <rjw@rjwysocki.net>
> CC: Murali Karicheri <m-karicheri2@ti.com>
> ---
>  drivers/of/of_pci.c    | 20 --------------------
>  drivers/pci/probe.c    | 35 +++++++++++++++++++++++++++++++++--
>  include/linux/of_pci.h |  3 ---
>  3 files changed, 33 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 5751dc5..b66ee4e 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -117,26 +117,6 @@ int of_get_pci_domain_nr(struct device_node *node)
>  }
>  EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
>  
> -/**
> - * of_pci_dma_configure - Setup DMA configuration
> - * @dev: ptr to pci_dev struct of the PCI device
> - *
> - * Function to update PCI devices's DMA configuration using the same
> - * info from the OF node of host bridge's parent (if any).
> - */
> -void of_pci_dma_configure(struct pci_dev *pci_dev)
> -{
> -	struct device *dev = &pci_dev->dev;
> -	struct device *bridge = pci_get_host_bridge_device(pci_dev);
> -
> -	if (!bridge->parent)
> -		return;
> -
> -	of_dma_configure(dev, bridge->parent->of_node);
> -	pci_put_host_bridge_device(bridge);
> -}
> -EXPORT_SYMBOL_GPL(of_pci_dma_configure);
> -
>  #if defined(CONFIG_OF_ADDRESS)
>  /**
>   * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 6675a7a..3c6f2e5 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -6,12 +6,14 @@
>  #include <linux/delay.h>
>  #include <linux/init.h>
>  #include <linux/pci.h>
> -#include <linux/of_pci.h>
> +#include <linux/of_device.h>
>  #include <linux/pci_hotplug.h>
>  #include <linux/slab.h>
>  #include <linux/module.h>
>  #include <linux/cpumask.h>
>  #include <linux/pci-aspm.h>
> +#include <linux/acpi.h>
> +#include <linux/property.h>
>  #include <asm-generic/pci-bridge.h>
>  #include "pci.h"
>  
> @@ -1508,6 +1510,35 @@ static void pci_init_capabilities(struct pci_dev *dev)
>  	pci_enable_acs(dev);
>  }
>  
> +/**
> + * pci_dma_configure - Setup DMA configuration
> + * @pci_dev: ptr to pci_dev struct of the PCI device
> + *
> + * Function to update PCI devices's DMA configuration using the same
> + * info from the OF node or ACPI node of host bridge's parent (if any).
> + */
> +static void pci_dma_configure(struct pci_dev *pci_dev)
> +{
> +	struct device *dev = &pci_dev->dev;
> +	struct device *bridge = pci_get_host_bridge_device(pci_dev);
> +	struct device *host = bridge->parent;
> +	struct acpi_device *adev;
> +
> +	if (!host)
> +		return;
> +
> +	if (acpi_disabled) {
> +		of_dma_configure(dev, host->of_node);

I'd rather do

	if (IS_ENABLED(CONFIG_OF) && host->of_node) {
		of_dma_configure(dev, host->of_node);
	} else {
		struct acpi_device *adev = ACPI_COMPANION(host);

		if (adev && acpi_dma_is_supported(adev)) {


> +	} else if (has_acpi_companion(host)) {
> +		adev = acpi_node(host->fwnode);
> +		if (acpi_dma_is_supported(adev))
> +			arch_setup_dma_ops(dev, 0, 0, NULL,
> +					   acpi_dma_is_coherent(adev));
> +	}
> +
> +	pci_put_host_bridge_device(bridge);
> +}
> +
>  void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>  {
>  	int ret;
> @@ -1521,7 +1552,7 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>  	dev->dev.dma_mask = &dev->dma_mask;
>  	dev->dev.dma_parms = &dev->dma_parms;
>  	dev->dev.coherent_dma_mask = 0xffffffffull;
> -	of_pci_dma_configure(dev);
> +	pci_dma_configure(dev);

Also I'm not quite sure if that's actually OK.

We should be handling the DMA setup on x86 in the ACPI case already without it.
Or is this a NOP on x86?

>  
>  	pci_set_dma_max_seg_size(dev, 65536);
>  	pci_set_dma_seg_boundary(dev, 0xffffffff);
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 29fd3fe..ce0e5ab 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -16,7 +16,6 @@ int of_pci_get_devfn(struct device_node *np);
>  int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
>  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
>  int of_get_pci_domain_nr(struct device_node *node);
> -void of_pci_dma_configure(struct pci_dev *pci_dev);
>  #else
>  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
>  {
> @@ -51,8 +50,6 @@ of_get_pci_domain_nr(struct device_node *node)
>  {
>  	return -1;
>  }
> -
> -static inline void of_pci_dma_configure(struct pci_dev *pci_dev) { }
>  #endif
>  
>  #if defined(CONFIG_OF_ADDRESS)
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.