Re: [RFC 2/2] usb: gadget: composite: parse dt overrides

On Mon, Jun 25, 2012 at 8:49 PM, Rob Herring [off-list ref] wrote:

On 06/25/2012 03:23 PM, Alexandre Pereira da Silva wrote:

quoted

Grab the devicetree node properties to override VendorId, ProductId,
bcdDevice, Manucacturer, Product and SerialNumber

Signed-off-by: Alexandre Pereira da Silva <redacted>
---
 drivers/usb/gadget/composite.c |   31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

Are these bindings documented? I think they should be less generic.
Perhaps prefixed with 'usb-'.

Not yet, I will in the final series. This was just to see it had big
issues because the final one needs to change lots of files.
I will add some prefix to them.

About the documentation, should I include it in all of the controllers
bindings or should I add a common file to describe the gadget drivers
binding?

quoted

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 390749b..f3b480e 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c

@@ -17,6 +17,7 @@

 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/utsname.h>
+#include <linux/of.h>

 #include <linux/usb/composite.h>
 #include <asm/unaligned.h>

@@ -1423,6 +1424,7 @@ static int composite_bind(struct usb_gadget *gadget)

 {
      struct usb_composite_dev        *cdev;
      int                             status = -ENOMEM;
+     struct device_node              *np = gadget->dev.of_node;

      cdev = kzalloc(sizeof *cdev, GFP_KERNEL);
      if (!cdev)

@@ -1470,6 +1472,35 @@ static int composite_bind(struct usb_gadget *gadget)

      cdev->desc = *composite->dev;

+     /* grab overrides from devicetree */

Reading the code, it looks more like the DT entries are defaults rather
than overrides.

Actually, it's mixed. The DT overrides the hard coded defaults. And
module parameters can override both. I think the safest path is to
keep them like this, so a DT would not break existing code.

quoted

+     if (np) {
+             u32 reg;
+
+             if (!idVendor &&
+                     of_property_read_u32(np, "vendor_id", &reg) == 0)
+                     idVendor = reg;

if (!idVendor)
       of_property_read_u32(np, "vendor_id", &idVendor);

Rob

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