Re: [PATCH v10 18/21] uvcvideo: improve error handling in uvc_query_ctrl()
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: 2021-08-22 23:52:48
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Hi Ricardo and Hans, Thank you for the patch. Please add a "media: " prefix to the subject line. Same for the other patches in the series that are missing this. On Fri, Jun 18, 2021 at 02:29:20PM +0200, Ricardo Ribalda wrote:
From: Hans Verkuil <redacted> - If __uvc_query_ctrl() failed with a non-EPIPE error, then report that with dev_err. If an error code is obtained, then report that with dev_dbg. - For error 2 (Wrong state) return -EACCES instead of -EILSEQ. EACCES is a much more appropriate error code. EILSEQ will return "Invalid or incomplete multibyte or wide character." in strerror(), which is a *very* confusing message.
I would still have split the patch in two :-)
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Reviewed-by: Ricardo Ribalda <redacted> Signed-off-by: Hans Verkuil <redacted> --- drivers/media/usb/uvc/uvc_video.c | 38 ++++++++++++++++++------------- 1 file changed, 22 insertions(+), 16 deletions(-)diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index daba5fe352ea..00488f15cdbf 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c@@ -79,15 +79,11 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, if (likely(ret == size)) return 0; - dev_err(&dev->udev->dev, - "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n", - uvc_query_name(query), cs, unit, ret, size); - - if (ret != -EPIPE) - return ret; + if (ret < 0 && ret != -EPIPE)
What if ret >= 0 ? There's a change of behaviour here that isn't documented in the commit message. It shouldn't happen, but it would be nice to handle it correctly.
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+ goto err; + /* reuse data[0] to request the error code. */ tmp = *(u8 *)data; - ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum, UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1, UVC_CTRL_CONTROL_TIMEOUT);@@ -95,19 +91,21 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, error = *(u8 *)data; *(u8 *)data = tmp; - if (ret != 1) - return ret < 0 ? ret : -EPIPE; + if (ret != 1) { + ret = ret < 0 ? ret : -EPIPE; + goto err;
This will print an error message that doesn't match the error.
+ } - uvc_dbg(dev, CONTROL, "Control error %u\n", error); + if (error >=1 && error <=8)
Missing space before 1 and 8.
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+ uvc_dbg(dev, CONTROL, + "Failed to query (%s) UVC control %u on unit %u: got error %u.\n", + uvc_query_name(query), cs, unit, error); switch (error) { - case 0: - /* Cannot happen - we received a STALL */ - return -EPIPE; case 1: /* Not ready */ return -EBUSY; case 2: /* Wrong state */ - return -EILSEQ; + return -EACCES; case 3: /* Power */ return -EREMOTE; case 4: /* Out of range */@@ -123,10 +121,18 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, case 8: /* Invalid value within range */ return -EINVAL; default: /* reserved or unknown */ - break; + dev_err(&dev->udev->dev, + "Failed to query (%s) UVC control %u on unit %u: got error %u.\n", + uvc_query_name(query), cs, unit, error); + return -EPIPE; } - return -EPIPE; +err: + dev_err(&dev->udev->dev, + "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n", + uvc_query_name(query), cs, unit, ret, size); + + return ret; } static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
-- Regards, Laurent Pinchart