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

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Date:   Tue, 7 Dec 2021 10:57:25 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>
Cc:     baolu.lu@...ux.intel.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
        Diana Craciun <diana.craciun@....nxp.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Li Yang <leoyang.li@....com>,
        Dmitry Osipenko <digetx@...il.com>,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 04/18] driver core: platform: Add driver dma ownership
 management

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
--- a/drivers/base/dd.c
+++ 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;
+                }
  	}

  	ret = driver_sysfs_add(dev);
@@ -660,6 +666,9 @@ 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);
+
+	if (dev->bus->dma_configure && !drv->no_kernel_dma)
+		iommu_device_release_dma_owner(dev, DMA_OWNER_DMA_API);
  pinctrl_bind_failed:
  	device_links_no_driver(dev);
  	devres_release_all(dev);
@@ -1204,6 +1213,9 @@ static void __device_release_driver(struct device 
*dev, struct device *parent)
  		else if (drv->remove)
  			drv->remove(dev);

+		if (dev->bus->dma_configure && !drv->no_kernel_dma)
+			iommu_device_release_dma_owner(dev, DMA_OWNER_DMA_API);
+
  		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..2cf7b757b28e 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 no_kernel_dma;
  	enum probe_type probe_type;

  	const struct of_device_id	*of_match_table;

Best regards,
baolu