Re: [PATCH v3 04/18] driver core: platform: Add driver dma ownership management

Lu Baolu
2021-12-09T01:20:29Z

On 12/7/21 9:16 PM, Jason Gunthorpe wrote:
> On Tue, Dec 07, 2021 at 10:57:25AM +0800, Lu Baolu wrote:
>> On 12/6/21 11:06 PM, Jason Gunthorpe wrote:
>>> On Mon, Dec 06, 2021 at 06:36:27AM -0800, Christoph Hellwig wrote:
>>>> 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?
>>>
>>
>> Are you talking about below change?
>>
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index 68ea1f949daa..368f9e530515 100644
>> +++ b/drivers/base/dd.c
>> @@ -577,7 +577,13 @@ static int really_probe(struct device *dev, struct
>> device_driver *drv)
>> if (dev->bus->dma_configure) {
>> ret = dev->bus->dma_configure(dev);
>> if (ret)
>> - goto probe_failed;
>> + goto pinctrl_bind_failed;
>> +
>> + if (!drv->no_kernel_dma) {
>> + ret = iommu_device_set_dma_owner(dev, DMA_OWNER_DMA_API, NULL);
>> + if (ret)
>> + goto pinctrl_bind_failed;
>> + }
>> }
>
> Yes, the suggestion was to put everything that 'if' inside a function
> and then of course a matching undo function.

Followed your suggestion, I refactored the change like below:

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,
NULL);
+}
+
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;

Further suggestions?

Best regards,
baolu