Re: [PATCH v10 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

Hi Robin

On 9/13/23 5:38 PM, Robin Murphy wrote:

On 2023-09-12 06:50, Umang Jain wrote:
[...]

quoted

quoted

quoted

+struct vchiq_device *
+vchiq_device_register(struct device *parent, const char *name)
+{
+    struct vchiq_device *device;
+    int ret;
+
+    device = kzalloc(sizeof(*device), GFP_KERNEL);
+    if (!device) {
+        dev_err(parent, "Cannot register %s: Insufficient memory\n",
+            name);
+        return NULL;
+    }
+
+    device->dev.init_name = name;
+    device->dev.parent = parent;
+    device->dev.bus = &vchiq_bus_type;
+    device->dev.release = vchiq_device_release;
+
+    of_dma_configure(&device->dev, parent->of_node, true);
+    ret = dma_set_mask_and_coherent(&device->dev, DMA_BIT_MASK(32));
+    if (ret) {
+        dev_err(&device->dev, "32-bit DMA enable failed\n");
+        return NULL;
+    }

Unfortunately the call of of_dma_configure() generates warnings likes
this (Raspberry Pi 3A+ with multi_v7_defconfig + VCHIQ):

[    9.206802] vchiq-bus bcm2835-audio: DMA mask not set
[    9.206892] vchiq-bus bcm2835-camera: DMA mask not set

huh, really weird, as on my RPi-3-b I get these set correctly and I 
don't any such warning.

Can you point to the code above where device->dev.dma_mask gets 
initialised between the initial kzalloc() and the call to 
of_dma_configure()? ;)

BTW, bus code shouldn't be calling dma_set_mask_and_coherent() on 
behalf of its children, that is for the individual drivers to do, if 
and when they intend to actually use DMA. Removing that here will save 
you needing to fix the memory leak as well...

Thanks for this suggestion. I have now set the dma_mask within the child 
itself!

Thanks,
Robin.

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