On Sun, Feb 23, 2025 at 08:32:24PM +0100, Ricardo Ribalda wrote:

On Sun, 23 Feb 2025 at 15:36, Laurent Pinchart wrote:

...

On Wed, Jan 29, 2025 at 12:39:46PM +0000, Ricardo Ribalda wrote:

...

uvc_gpio_parse() can return -EPROBE_DEFER when the GPIOs it depends on have not yet been probed. This return code should be propagated to the caller of uvc_probe() to ensure that probing is retried when the required GPIOs become available.

Currently, this error code is incorrectly converted to -ENODEV, causing some internal cameras to be ignored.

This commit fixes this issue by propagating the -EPROBE_DEFER error.

Cc: stable@vger.kernel.org Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT") Signed-off-by: Ricardo Ribalda ribalda@chromium.org

---

drivers/media/usb/uvc/uvc_driver.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index a10d4f4d9f95..73a7f23b616c 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2253,9 +2253,10 @@ static int uvc_probe(struct usb_interface *intf, }

  /* Parse the associated GPIOs. */

• if (uvc_gpio_parse(dev) < 0) {
  

• ret = uvc_gpio_parse(dev);
  

• if (ret < 0) {
          uvc_dbg(dev, PROBE, "Unable to parse UVC GPIOs\n");
  

•         goto error;
  

•         goto error_retcode;
  }
  
  dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
  

@@ -2328,9 +2329,11 @@ static int uvc_probe(struct usb_interface *intf, return 0;

error:

• ret = -ENODEV;
  

+error_retcode:

This isn't very nice. Could we instead also propagate error codes from other locations in the uvc_probe() function ? If you want to minimize changes, you can initialize ret to -ENODEV, and turn the (ret < 0) check for uvc_gpio_parse() to a (ret) check.

Not very nice, but easy to backport to stables. What about a follow-up change like this:

How about the nicer fix for mainline, and a simpler to backport one for stable ? The main focus should be on mainline, not backports.

index c93abe2367aa..8c67feca1688 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2261,7 +2261,7 @@ static int uvc_probe(struct usb_interface *intf, ret = uvc_gpio_parse(dev); if (ret < 0) { uvc_dbg(dev, PROBE, "Unable to parse UVC GPIOs\n");

•           goto error_retcode;
  

•           goto error;
    }
  
    dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
  

@@ -2285,24 +2285,32 @@ static int uvc_probe(struct usb_interface *intf, }

    /* Register the V4L2 device. */

•   if (v4l2_device_register(&intf->dev, &dev->vdev) < 0)
  

•   ret = v4l2_device_register(&intf->dev, &dev->vdev);
  

•   if (ret < 0)
            goto error;
  
    /* Scan the device for video chains. */
  

•   if (uvc_scan_device(dev) < 0)
  

•   if (uvc_scan_device(dev) < 0) {
  

•           ret = -ENODEV;
            goto error;
  

•   }
  
    /* Initialize controls. */
  

•   if (uvc_ctrl_init_device(dev) < 0)
  

•   if (uvc_ctrl_init_device(dev) < 0) {
  

•           ret = -ENODEV;
            goto error;
  

•   }
  
    /* Register video device nodes. */
  

•   if (uvc_register_chains(dev) < 0)
  

•   if (uvc_register_chains(dev) < 0) {
  

•           ret = -ENODEV;
            goto error;
  

•   }
  
  

#ifdef CONFIG_MEDIA_CONTROLLER /* Register the media device node */

•   if (media_device_register(&dev->mdev) < 0)
  

•   ret = media_device_register(&dev->mdev);
  

•   if (ret < 0)
            goto error;
  

#endif /* Save our data pointer in the interface data. */ @@ -2334,8 +2342,6 @@ static int uvc_probe(struct usb_interface *intf, return 0;

error:

•   ret = -ENODEV;
  

-error_retcode: uvc_unregister_video(dev); kref_put(&dev->ref, uvc_delete); return ret;

...

...

  uvc_unregister_video(dev);
  kref_put(&dev->ref, uvc_delete);

• return -ENODEV;
  

• return ret;
  

}

static void uvc_disconnect(struct usb_interface *intf)

---

base-commit: c4b7779abc6633677e6edb79e2809f4f61fde157 change-id: 20250129-uvc-eprobedefer-b5ebb4db63cc

-- Regards,

Laurent Pinchart

Let me know what do you think so I can send a v2 with the change proposed by Doug.

Regards!