Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Greg KH]

On Fri, Mar 30, 2018 at 09:15:30AM +0200, Christoph Hellwig wrote:
> Can you resend the current state of affairs so we can get it in for
> 4.17?

Changes to the driver core and 3 different busses 2 days before 4.16 is
out, preventing any testing at all in linux-next?  This needs to wait
for the next merge window, sorry.  I'm away all this weekend, and can't
test on my end, sorry.

greg k-h
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RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Nipun Gupta]

I am just going to send it within an hour :)

Thanks,
Nipun

> -Original Message-
> From: Christoph Hellwig [mailto:h...@lst.de]
> Sent: Friday, March 30, 2018 12:46
> To: Nipun Gupta <nipun.gu...@nxp.com>
> Cc: h...@lst.de; robin.mur...@arm.com; li...@armlinux.org.uk;
> gre...@linuxfoundation.org; m.szyprow...@samsung.com; bhelg...@google.com;
> dmitry.torok...@gmail.com; rafael.j.wyso...@intel.com;
> jarkko.sakki...@linux.intel.com; linus.wall...@linaro.org;
> jo...@kernel.org; msucha...@suse.de; linux-ker...@vger.kernel.org;
> iommu@lists.linux-foundation.org; linux-...@vger.kernel.org
> Subject: Re: [PATCH] dma-mapping: move dma configuration to bus
> infrastructure
> 
> Can you resend the current state of affairs so we can get it in for
> 4.17?
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Christoph Hellwig]

Can you resend the current state of affairs so we can get it in for
4.17?
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Christoph Hellwig]

> Agree. There is no good point in duplicating the code.
> So this new API will be part of 'drivers/base/dma-mapping.c' file?

Yes.

> > As mention in my previous reply I think we don't even need a deconfigure
> > callback at this point - just remove the ACPI and OF wrappers and
> > clear the dma ops.
> > 
> > Also in this series we should replace the force_dma flag by use of the
> > proper method, e.g. give a force parameter to of_dma_configure and the
> > new dma_common_configure helper that the busses that want it can set.
> 
> I am more inclined to what Robin states in other mail to keep symmetry.
> i.e. to keep dma_configure() and dma_deconfigure() and call
> dev->bus->dma_configure from dma_configure(). Is this okay?

Sure.
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Christoph Hellwig]

>> +.dev_groups = amba_dev_groups,
>> +.match  = amba_match,
>> +.uevent = amba_uevent,
>> +.pm = _pm,
>> +.dma_configure  = amba_dma_configure,
>> +.dma_deconfigure= amba_dma_deconfigure,
>> +.force_dma  = true,
>
> This patch should also be removing force_dma because it no longer makes 
> sense. If DMA configuration is now done by a bus-level callback, then a bus 
> which wants its children to get DMA configuration needs to implement that 
> callback; there's nowhere to force a "default" global behaviour any more.

Btw, we don't really know how many busses currently rely on OF or ACPI
configuration.  So maybe we need to keep those as a default?
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[kbuild test robot]

Hi Nipun,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v4.16-rc5 next-20180313]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improve the system]

url:
https://github.com/0day-ci/linux/commits/Nipun-Gupta/dma-mapping-move-dma-configuration-to-bus-infrastructure/20180313-225250
reproduce:
# apt-get install sparse
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

>> drivers/base/platform.c:1133:5: sparse: symbol 'platform_dma_configure' was 
>> not declared. Should it be static?
>> drivers/base/platform.c:1149:6: sparse: symbol 'platform_dma_deconfigure' 
>> was not declared. Should it be static?

Please review and possibly fold the followup patch.

---
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https://lists.01.org/pipermail/kbuild-all   Intel Corporation
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RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Nipun Gupta]

> -Original Message-
> From: Robin Murphy [mailto:robin.mur...@arm.com]
> Sent: Tuesday, March 13, 2018 17:06
> 
> On 12/03/18 15:24, Nipun Gupta wrote:
> > The change introduces 'dma_configure' & 'dma_deconfigure'as
> > bus callback functions so each bus can choose to implement
> > its own dma configuration function.
> > This eases the addition of new busses w.r.t. adding the dma
> > configuration functionality.
> 
> It's probably worth clarifying - either in the commit message, the
> kerneldoc, or both - that the bus-specific aspect is that of mapping
> between a given device on the bus and the relevant firmware description
> of its DMA configuration.

Okay.

>
> > The change also updates the PCI, Platform and ACPI bus to use
> > new introduced callbacks.
> >
> > Signed-off-by: Nipun Gupta 
> > ---
> >   - This patch is based on the comments on:
> >
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwo
> rk.kernel.org%2Fpatch%2F10259087%2F=02%7C01%7Cnipun.gupta%40nxp.com%7
> Cc541100ecb944e7650a408d588d69ab0%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7
> C0%7C636565377665676631=k2Xjn5B1GECx4UjCg9tChOpOrD3NPM7BkzIXLLSv3rI%
> 3D=0
> >   - I have validated for PCI and platform, but not for AMBA as I
> > do not have infrastructure to validate it.
> > Can anyone please validate them on AMBA?
> >
> >   drivers/amba/bus.c  | 38 -
> >   drivers/base/dd.c   | 14 +++
> >   drivers/base/dma-mapping.c  | 41 ---
> >   drivers/base/platform.c | 36 ++-
> >   drivers/pci/pci-driver.c| 59 -
> 
> >   include/linux/device.h  |  6 +
> >   include/linux/dma-mapping.h | 12 -
> >   7 files changed, 124 insertions(+), 82 deletions(-)
> >
> > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> > index 594c228..58241d2 100644
> > --- a/drivers/amba/bus.c
> > +++ b/drivers/amba/bus.c
> > @@ -20,6 +20,8 @@
> >   #include 
> >   #include 
> >   #include 
> > +#include 
> > +#include 
> >
> >   #include 
> >
> > @@ -171,6 +173,28 @@ static int amba_pm_runtime_resume(struct device
> *dev)
> >   }
> >   #endif /* CONFIG_PM */
> >
> > +int amba_dma_configure(struct device *dev)
> > +{
> > +   enum dev_dma_attr attr;
> > +   int ret = 0;
> > +
> > +   if (dev->of_node) {
> > +   ret = of_dma_configure(dev, dev->of_node);
> > +   } else if (has_acpi_companion(dev)) {
> > +   attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
> > +   if (attr != DEV_DMA_NOT_SUPPORTED)
> > +   ret = acpi_dma_configure(dev, attr);
> > +   }
> > +
> > +   return ret;
> > +}
> 
> I would be inclined to have amba_bustype just reference
> platform_dma_configure() directly rather than duplicate it like this,
> since there's no sensible reason for them to ever differ.

I think dma_common_configure() having this as the common code seems pretty
Decent. All the busses will probably call this API.

> 
> > +
> > +void amba_dma_deconfigure(struct device *dev)
> > +{
> > +   of_dma_deconfigure(dev);
> > +   acpi_dma_deconfigure(dev);
> > +}
> > +
> >   static const struct dev_pm_ops amba_pm = {
> > .suspend= pm_generic_suspend,
> > .resume = pm_generic_resume,
> > @@ -190,12 +214,14 @@ static int amba_pm_runtime_resume(struct device
> *dev)
> >* so we call the bus "amba".
> >*/
> >   struct bus_type amba_bustype = {
> > -   .name   = "amba",
> > -   .dev_groups = amba_dev_groups,
> > -   .match  = amba_match,
> > -   .uevent = amba_uevent,
> > -   .pm = _pm,
> > -   .force_dma  = true,
> > +   .name   = "amba",
> > +   .dev_groups = amba_dev_groups,
> > +   .match  = amba_match,
> > +   .uevent = amba_uevent,
> > +   .pm = _pm,
> > +   .dma_configure  = amba_dma_configure,
> > +   .dma_deconfigure= amba_dma_deconfigure,
> > +   .force_dma  = true,
> 
> This patch should also be removing force_dma because it no longer makes
> sense. If DMA configuration is now done by a bus-level callback, then a
> bus which wants its children to get DMA configuration needs to implement
> that callback; there's nowhere to force a "default" global behaviour any
> more.

Agree. We will also need to pass a force_dma flag in of_dma_configure() as
Christoph suggests. Ill update this.

> 
> >   };
> >
> >   static int __init amba_init(void)
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> > index de6fd09..f124f3f 100644
> > --- a/drivers/base/dd.c
> > +++ b/drivers/base/dd.c
> > @@ -421,9 +421,11 @@ static int really_probe(struct device *dev, struct
> device_driver *drv)
> > if (ret)
> > goto pinctrl_bind_failed;
> >
> > -   ret = dma_configure(dev);
> > -   if (ret)
> > -   goto dma_failed;
> > +   if 

RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Nipun Gupta]

> -Original Message-
> From: Christoph Hellwig [mailto:h...@lst.de]
> Sent: Tuesday, March 13, 2018 13:05
> > +int amba_dma_configure(struct device *dev)
> > +{
> > +   enum dev_dma_attr attr;
> > +   int ret = 0;
> > +
> > +   if (dev->of_node) {
> > +   ret = of_dma_configure(dev, dev->of_node);
> > +   } else if (has_acpi_companion(dev)) {
> > +   attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
> > +   if (attr != DEV_DMA_NOT_SUPPORTED)
> > +   ret = acpi_dma_configure(dev, attr);
> > +   }
> > +
> > +   return ret;
> 
> This code sniplet is duplicated so many times that I think we should
> just have some sort of dma_common_configure() for it that the various
> busses can use.

Agree. There is no good point in duplicating the code.
So this new API will be part of 'drivers/base/dma-mapping.c' file?

> 
> > +void amba_dma_deconfigure(struct device *dev)
> > +{
> > +   of_dma_deconfigure(dev);
> > +   acpi_dma_deconfigure(dev);
> > +}
> 
> As mention in my previous reply I think we don't even need a deconfigure
> callback at this point - just remove the ACPI and OF wrappers and
> clear the dma ops.
> 
> Also in this series we should replace the force_dma flag by use of the
> proper method, e.g. give a force parameter to of_dma_configure and the
> new dma_common_configure helper that the busses that want it can set.

I am more inclined to what Robin states in other mail to keep symmetry.
i.e. to keep dma_configure() and dma_deconfigure() and call
dev->bus->dma_configure from dma_configure(). Is this okay?

Thanks,
Nipun
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Robin Murphy]

On 12/03/18 15:24, Nipun Gupta wrote:

The change introduces 'dma_configure' & 'dma_deconfigure'as
bus callback functions so each bus can choose to implement
its own dma configuration function.
This eases the addition of new busses w.r.t. adding the dma
configuration functionality.


It's probably worth clarifying - either in the commit message, the 
kerneldoc, or both - that the bus-specific aspect is that of mapping 
between a given device on the bus and the relevant firmware description 
of its DMA configuration.



The change also updates the PCI, Platform and ACPI bus to use
new introduced callbacks.

Signed-off-by: Nipun Gupta 
---
  - This patch is based on the comments on:
https://patchwork.kernel.org/patch/10259087/
  - I have validated for PCI and platform, but not for AMBA as I
do not have infrastructure to validate it.
Can anyone please validate them on AMBA?

  drivers/amba/bus.c  | 38 -
  drivers/base/dd.c   | 14 +++
  drivers/base/dma-mapping.c  | 41 ---
  drivers/base/platform.c | 36 ++-
  drivers/pci/pci-driver.c| 59 -
  include/linux/device.h  |  6 +
  include/linux/dma-mapping.h | 12 -
  7 files changed, 124 insertions(+), 82 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 594c228..58241d2 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -20,6 +20,8 @@
  #include 
  #include 
  #include 
+#include 
+#include 
  
  #include 
  
@@ -171,6 +173,28 @@ static int amba_pm_runtime_resume(struct device *dev)

  }
  #endif /* CONFIG_PM */
  
+int amba_dma_configure(struct device *dev)

+{
+   enum dev_dma_attr attr;
+   int ret = 0;
+
+   if (dev->of_node) {
+   ret = of_dma_configure(dev, dev->of_node);
+   } else if (has_acpi_companion(dev)) {
+   attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
+   if (attr != DEV_DMA_NOT_SUPPORTED)
+   ret = acpi_dma_configure(dev, attr);
+   }
+
+   return ret;
+}


I would be inclined to have amba_bustype just reference 
platform_dma_configure() directly rather than duplicate it like this, 
since there's no sensible reason for them to ever differ.



+
+void amba_dma_deconfigure(struct device *dev)
+{
+   of_dma_deconfigure(dev);
+   acpi_dma_deconfigure(dev);
+}
+
  static const struct dev_pm_ops amba_pm = {
.suspend= pm_generic_suspend,
.resume = pm_generic_resume,
@@ -190,12 +214,14 @@ static int amba_pm_runtime_resume(struct device *dev)
   * so we call the bus "amba".
   */
  struct bus_type amba_bustype = {
-   .name   = "amba",
-   .dev_groups = amba_dev_groups,
-   .match  = amba_match,
-   .uevent = amba_uevent,
-   .pm = _pm,
-   .force_dma  = true,
+   .name   = "amba",
+   .dev_groups = amba_dev_groups,
+   .match  = amba_match,
+   .uevent = amba_uevent,
+   .pm = _pm,
+   .dma_configure  = amba_dma_configure,
+   .dma_deconfigure= amba_dma_deconfigure,
+   .force_dma  = true,


This patch should also be removing force_dma because it no longer makes 
sense. If DMA configuration is now done by a bus-level callback, then a 
bus which wants its children to get DMA configuration needs to implement 
that callback; there's nowhere to force a "default" global behaviour any 
more.



  };
  
  static int __init amba_init(void)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index de6fd09..f124f3f 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -421,9 +421,11 @@ static int really_probe(struct device *dev, struct 
device_driver *drv)
if (ret)
goto pinctrl_bind_failed;
  
-	ret = dma_configure(dev);

-   if (ret)
-   goto dma_failed;
+   if (dev->bus->dma_configure) {
+   ret = dev->bus->dma_configure(dev);
+   if (ret)
+   goto dma_failed;
+   }
  
  	if (driver_sysfs_add(dev)) {

printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
@@ -486,7 +488,8 @@ static int really_probe(struct device *dev, struct 
device_driver *drv)
goto done;
  
  probe_failed:

-   dma_deconfigure(dev);
+   if (dev->bus->dma_deconfigure)
+   dev->bus->dma_deconfigure(dev);
  dma_failed:
if (dev->bus)
blocking_notifier_call_chain(>bus->p->bus_notifier,
@@ -895,7 +898,8 @@ static void __device_release_driver(struct device *dev, 
struct device *parent)
drv->remove(dev);
  
  		device_links_driver_cleanup(dev);

-   dma_deconfigure(dev);
+   if (dev->bus->dma_deconfigure)
+  

Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Christoph Hellwig]

> +int amba_dma_configure(struct device *dev)
> +{
> + enum dev_dma_attr attr;
> + int ret = 0;
> +
> + if (dev->of_node) {
> + ret = of_dma_configure(dev, dev->of_node);
> + } else if (has_acpi_companion(dev)) {
> + attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
> + if (attr != DEV_DMA_NOT_SUPPORTED)
> + ret = acpi_dma_configure(dev, attr);
> + }
> +
> + return ret;

This code sniplet is duplicated so many times that I think we should
just have some sort of dma_common_configure() for it that the various
busses can use.

> +void amba_dma_deconfigure(struct device *dev)
> +{
> + of_dma_deconfigure(dev);
> + acpi_dma_deconfigure(dev);
> +}

As mention in my previous reply I think we don't even need a deconfigure
callback at this point - just remove the ACPI and OF wrappers and
clear the dma ops.

Also in this series we should replace the force_dma flag by use of the
proper method, e.g. give a force parameter to of_dma_configure and the
new dma_common_configure helper that the busses that want it can set.
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[h...@lst.de]

On Tue, Mar 13, 2018 at 04:22:53AM +, Nipun Gupta wrote:
> > Isn't this one or the other one but not both?
> > 
> > Something like:
> > 
> > if (dev->of_node)
> > of_dma_deconfigure(dev);
> > else
> > acpi_dma_deconfigure(dev);
> > 
> > should work.
> 
> I understand your point. Seems reasonable as we should not expect
> the 'of/acpi DMA deconfigure' API to not fail when they are not configured.
> 
> But, here we would also need to get dma_device (just as we get in
> 'pci_dma_configure') and need a check on it as for PCI there 'of_node'
> is present in the dma_dev.

Both of_dma_deconfigure and acpi_dma_deconfigure just end up calling
arch_teardown_dma_ops.  So my preference would be to just remove
of_dma_deconfigure and acpi_dma_deconfigure and call arch_teardown_dma_ops
as a prep patch before this one.
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RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Nipun Gupta]

> -Original Message-
> From: Sinan Kaya [mailto:ok...@codeaurora.org]
> Sent: Monday, March 12, 2018 22:14
> To: Nipun Gupta <nipun.gu...@nxp.com>; h...@lst.de;
> robin.mur...@arm.com; li...@armlinux.org.uk; gre...@linuxfoundation.org;
> m.szyprow...@samsung.com; bhelg...@google.com
> Cc: dmitry.torok...@gmail.com; rafael.j.wyso...@intel.com;
> jarkko.sakki...@linux.intel.com; linus.wall...@linaro.org; jo...@kernel.org;
> msucha...@suse.de; linux-ker...@vger.kernel.org; iommu@lists.linux-
> foundation.org; linux-...@vger.kernel.org
> Subject: Re: [PATCH] dma-mapping: move dma configuration to bus
> infrastructure
> 
> On 3/12/2018 11:24 AM, Nipun Gupta wrote:
> > +   if (dma_dev->of_node) {
> > +   ret = of_dma_configure(dev, dma_dev->of_node);
> > +   } 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)
> > +   ret = acpi_dma_configure(dev, attr);
> > +   }
> > +
> > +   pci_put_host_bridge_device(bridge);
> > +
> > +   return ret;
> > +}
> > +
> > +void pci_dma_deconfigure(struct device *dev)
> > +{
> > +   of_dma_deconfigure(dev);
> > +   acpi_dma_deconfigure(dev);
> > +}
> 
> Isn't this one or the other one but not both?
> 
> Something like:
> 
> if (dev->of_node)
>   of_dma_deconfigure(dev);
> else
>   acpi_dma_deconfigure(dev);
> 
> should work.

I understand your point. Seems reasonable as we should not expect
the 'of/acpi DMA deconfigure' API to not fail when they are not configured.

But, here we would also need to get dma_device (just as we get in
'pci_dma_configure') and need a check on it as for PCI there 'of_node'
is present in the dma_dev.

Ill update this in v2, and also make similar changes for platform and AMBA bus.

Thanks,
Nipun

> 
> --
> Sinan Kaya
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
> Technologies, Inc.
> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
> Foundation Collaborative Project.
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Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure

[Sinan Kaya]

On 3/12/2018 11:24 AM, Nipun Gupta wrote:
> + if (dma_dev->of_node) {
> + ret = of_dma_configure(dev, dma_dev->of_node);
> + } 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)
> + ret = acpi_dma_configure(dev, attr);
> + }
> +
> + pci_put_host_bridge_device(bridge);
> +
> + return ret;
> +}
> +
> +void pci_dma_deconfigure(struct device *dev)
> +{
> + of_dma_deconfigure(dev);
> + acpi_dma_deconfigure(dev);
> +}

Isn't this one or the other one but not both?

Something like:

if (dev->of_node)
of_dma_deconfigure(dev);
else
acpi_dma_deconfigure(dev);

should work.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm 
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux 
Foundation Collaborative Project.
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