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[209.85.166.178]) by smtp.gmail.com with ESMTPSA id l14sm2840238ilc.33.2021.03.25.07.02.56 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Mar 2021 07:02:57 -0700 (PDT) Received: by mail-il1-f178.google.com with SMTP id r8so2195458ilo.8 for ; Thu, 25 Mar 2021 07:02:56 -0700 (PDT) X-Received: by 2002:a92:3648:: with SMTP id d8mr6359874ilf.69.1616680976507; Thu, 25 Mar 2021 07:02:56 -0700 (PDT) MIME-Version: 1.0 References: <347cdb4a-19a2-98ce-580f-5aba4abfb2fc@xs4all.nl> <35f1fa6e-a498-9217-5359-82b58dec61f6@xs4all.nl> <8a265a15-c9f6-bea4-1a38-df675a977e8c@xs4all.nl> In-Reply-To: <8a265a15-c9f6-bea4-1a38-df675a977e8c@xs4all.nl> From: Ricardo Ribalda Date: Thu, 25 Mar 2021 15:02:45 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] uvcvideo: improve error handling in uvc_query_ctrl() To: Hans Verkuil Cc: Ricardo Ribalda Delgado , Linux Media Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Hans On Thu, Mar 25, 2021 at 2:57 PM Hans Verkuil wrote: > > On 25/03/2021 14:54, Ricardo Ribalda wrote: > > hi Hans > > > > On Thu, Mar 25, 2021 at 1:18 PM Hans Verkuil wrote: > >> > >> On 23/03/2021 16:25, Ricardo Ribalda Delgado wrote: > >>> Hi Hans > >>> > >>> Thanks for the patch. I like how uvc is ending :) > >>> > >>> On Mon, Mar 22, 2021 at 1:09 PM Hans Verkuil wrote: > >>>> > >>>> - 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. > >>>> > >>>> Signed-off-by: Hans Verkuil > >>>> --- > >>>> Ricardo, this too can be added to the uvc series. > >>>> --- > >>>> drivers/media/usb/uvc/uvc_video.c | 44 +++++++++++++++++-------------- > >>>> 1 file changed, 24 insertions(+), 20 deletions(-) > >>>> > >>>> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > >>>> index b63c073ec30e..3f461bb4eeb9 100644 > >>>> --- a/drivers/media/usb/uvc/uvc_video.c > >>>> +++ b/drivers/media/usb/uvc/uvc_video.c > >>>> @@ -68,7 +68,7 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, > >>>> u8 intfnum, u8 cs, void *data, u16 size) > >>>> { > >>>> int ret; > >>>> - u8 error; > >>>> + u8 error = 0; > >>>> u8 tmp; > >>>> > >>>> ret = __uvc_query_ctrl(dev, query, unit, intfnum, cs, data, size, > >>>> @@ -76,35 +76,39 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, > >>>> if (likely(ret == size)) > >>>> return 0; > >>>> > >>>> - dev_dbg(&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); > >>>> + ret = ret < 0 ? ret : -EPIPE; > >>>> > >>>> - if (ret != -EPIPE) > >>>> - return ret; > >>>> - > >>>> - tmp = *(u8 *)data; > >>>> + if (ret == -EPIPE) { > >>>> + 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); > >>>> + ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum, > >>>> + UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1, > >>>> + UVC_CTRL_CONTROL_TIMEOUT); > >>>> > >>>> - error = *(u8 *)data; > >>>> - *(u8 *)data = tmp; > >>>> + if (ret == 1) > >>>> + error = *(u8 *)data; > >>>> + *(u8 *)data = tmp; > >>>> + if (ret != 1) > >>>> + ret = ret < 0 ? ret : -EPIPE; > >>>> + } > >>>> > >>>> - if (ret != 1) > >>>> - return ret < 0 ? ret : -EPIPE; > >>>> + if (error) > >>>> + dev_dbg(&dev->udev->dev, > >>>> + "Failed to query (%s) UVC control %u on unit %u: got error %u.\n", > >>>> + uvc_query_name(query), cs, unit, error); > >>>> + else > >>>> + 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 __uvc_query_ctrl and UVC_VC_REQUEST_ERROR_CODE_CONTROL failed, > >>> error is 0. And I think that you want to show a dev_err in that case. > >>> Maybe we can initialize error to 7 ? > >> > >> I'm confused, if error == 0, then it does show dev_err. > > > > My bad. > > > > Ignore the message. > > > > Can we write it as ?: > > > > if (!error) { > > dev_dbg(&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 ret; > > } > > > > 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); > > Sure! Just take this patch as inspiration :-) Do you mind if I modify it before resend? > > Regards, > > Hans > > > > > > > > >> > >>> > >>> > >>>> > >>>> - uvc_dbg(dev, CONTROL, "Control error %u\n", error); > >>>> + if (!error) > >>>> + return ret; > >>> I think we do not want these two lines (read next comment) > >>>> > >>>> 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 */ > >>> > >>> Maybe we want a dev_dbg if the error code is unknown and return ret? > >> > >> Make sense. > >> > >> Regards, > >> > >> Hans > > > > > > > -- Ricardo Ribalda