Hi Greg,

On 2021/12/13 8:50, Lu Baolu wrote:

On 12/10/21 9:23 AM, Lu Baolu wrote:

quoted

Hi Greg, Jason and Christoph,

On 12/9/21 9:20 AM, Lu Baolu wrote:

quoted

On 12/7/21 9:16 PM, Jason Gunthorpe wrote:

quoted

On Tue, Dec 07, 2021 at 10:57:25AM +0800, Lu Baolu wrote:

quoted

On 12/6/21 11:06 PM, Jason Gunthorpe wrote:

quoted

On Mon, Dec 06, 2021 at 06:36:27AM -0800, Christoph Hellwig wrote:

quoted

I really hate the amount of boilerplate code that having this in 
each
bus type causes.

+1

I liked the first version of this series better with the code near
really_probe().

Can we go back to that with some device_configure_dma() wrapper
condtionally called by really_probe as we discussed?

[...]

quoted

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 68ea1f949daa..68ca5a579eb1 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c

@@ -538,6 +538,32 @@ static int call_driver_probe(struct device *dev, 

struct device_driver *drv)
         return ret;
  }

+static int device_dma_configure(struct device *dev, struct 
device_driver *drv)
+{
+       int ret;
+
+       if (!dev->bus->dma_configure)
+               return 0;
+
+       ret = dev->bus->dma_configure(dev);
+       if (ret)
+               return ret;
+
+       if (!drv->suppress_auto_claim_dma_owner)
+               ret = iommu_device_set_dma_owner(dev, 
DMA_OWNER_DMA_API, NULL);
+
+       return ret;
+}
+
+static void device_dma_cleanup(struct device *dev, struct 
device_driver *drv)
+{
+       if (!dev->bus->dma_configure)
+               return;
+
+       if (!drv->suppress_auto_claim_dma_owner)
+               iommu_device_release_dma_owner(dev, DMA_OWNER_DMA_API);
+}
+
  static int really_probe(struct device *dev, struct device_driver *drv)
  {
         bool test_remove = 
IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&

@@ -574,11 +600,8 @@ static int really_probe(struct device *dev, 

struct device_driver *drv)
         if (ret)
                 goto pinctrl_bind_failed;

-       if (dev->bus->dma_configure) {
-               ret = dev->bus->dma_configure(dev);
-               if (ret)
-                       goto probe_failed;
-       }
+       if (device_dma_configure(dev, drv))
+               goto pinctrl_bind_failed;

         ret = driver_sysfs_add(dev);
         if (ret) {

@@ -660,6 +683,8 @@ static int really_probe(struct device *dev, 

struct device_driver *drv)
         if (dev->bus)
                 
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,

BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
+
+       device_dma_cleanup(dev, drv);
  pinctrl_bind_failed:
         device_links_no_driver(dev);
         devres_release_all(dev);

@@ -1204,6 +1229,7 @@ static void __device_release_driver(struct 

device *dev, struct device *parent)
                 else if (drv->remove)
                         drv->remove(dev);

+               device_dma_cleanup(dev, drv);
                 device_links_driver_cleanup(dev);

                 devres_release_all(dev);

diff --git a/include/linux/device/driver.h 

b/include/linux/device/driver.h
index a498ebcf4993..374a3c2cc10d 100644

--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h

@@ -100,6 +100,7 @@ struct device_driver {

         const char              *mod_name;      /* used for built-in 
modules */

         bool suppress_bind_attrs;       /* disables bind/unbind via 
sysfs */
+       bool suppress_auto_claim_dma_owner;
         enum probe_type probe_type;

         const struct of_device_id       *of_match_table;

Does this work for you? Can I work towards this in the next version?

A kindly ping ... Is this heading the right direction? I need your
advice to move ahead. :-)

Can I do it like this? :-)

Best regards,
baolu