Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20181008145012.31312-1-colin.king@canonical.com>
 <d753df4f-e812-c366-0b1d-9ff804da0ab5@i2se.com> <CAAoAYcO=qp7yb7392B_6wks2j2TaoxYXHtQPyH0kMkFMi+JW-A@mail.gmail.com>
 <663860283.72238.1539018547916@email.1und1.de>
In-Reply-To: <663860283.72238.1539018547916@email.1und1.de>
From:   Dave Stevenson <dave.stevenson@raspberrypi.org>
Date:   Mon, 8 Oct 2018 18:20:17 +0100
Message-ID: <CAAoAYcNMJd2429fZWd_E3w=MhBdZDADNtHkVtf1__VVcjSEBTg@mail.gmail.com>
Subject: Re: [PATCH] staging: bcm2835-camera: remove extraneous setting of dev->colourfx.enable
To:     Stefan Wahren <stefan.wahren@i2se.com>
Cc:     colin.king@canonical.com, Eric Anholt <eric@anholt.net>,
        Greg KH <gregkh@linuxfoundation.org>,
        bcm-kernel-feedback-list@broadcom.com,
        "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@lists.infradead.org>,
        linux-arm-kernel@lists.infradead.org, devel@driverdev.osuosl.org,
        kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 8 Oct 2018 at 18:09, Stefan Wahren <stefan.wahren@i2se.com> wrote:
>
> Hi Dave,
>
> > Dave Stevenson <dave.stevenson@raspberrypi.org> hat am 8. Oktober 2018 um 18:51 geschrieben:
> >
> >
> >  Hi Stefan.
> >
> > Thanks for forwarding as the linux-rpi-kernel list hasn't sent it to me as yet.
>
> AFAIK every mail with more than 5 recipients will be delayed.
>
> >
> > On Mon, 8 Oct 2018 at 16:48, Stefan Wahren <stefan.wahren@i2se.com> wrote:
> > >
> > > Hi Colin,
> > >
> > > Am 08.10.2018 um 16:50 schrieb Colin King:
> > > > From: Colin Ian King <colin.king@canonical.com>
> > > >
> > > > Currently dev->colourfx.enable is being set twice, hence the first
> > > > occurrance is redundant and can be removed, so remove it. This minor
> > > > issue was introduced by commit 7b3ad5abf027 ("staging: Import the
> > > > BCM2835 MMAL-based V4L2 camera driver.").
> > > >
> > > > Detected by CoverityScan CID#1419711 ("Unused value")
> > > >
> > > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > > > ---
> > > >  drivers/staging/vc04_services/bcm2835-camera/controls.c | 1 -
> > > >  1 file changed, 1 deletion(-)
> > > >
> > > > diff --git a/drivers/staging/vc04_services/bcm2835-camera/controls.c b/drivers/staging/vc04_services/bcm2835-camera/controls.c
> > > > index a2c55cb2192a..99831dd4365d 100644
> > > > --- a/drivers/staging/vc04_services/bcm2835-camera/controls.c
> > > > +++ b/drivers/staging/vc04_services/bcm2835-camera/controls.c
> > > > @@ -588,7 +588,6 @@ static int ctrl_set_colfx(struct bm2835_mmal_dev *dev,
> > > >
> > > >       control = &dev->component[MMAL_COMPONENT_CAMERA]->control;
> > > >
> > > > -     dev->colourfx.enable = (ctrl->val & 0xff00) >> 8;
> > > >       dev->colourfx.enable = ctrl->val & 0xff;
> > > >
> > > >       ret = vchiq_mmal_port_parameter_set(dev->instance, control,
> > >
> > > as long as the current behavior is correct, i'm okay with this patch.
> > > But the byte masking looks suspicious, so i hope Dave can clarify that.
> >
> > It's writing to the wrong structure member.
> > The function is used on the V4L2 control V4L2_CID_COLORFX_CBCR, which
> > is defined as:
> > V4L2_CID_COLORFX_CBCR (integer)
> > Determines the Cb and Cr coefficients for V4L2_COLORFX_SET_CBCR color
> > effect. Bits [7:0] of the supplied 32 bit value are interpreted as Cr
> > component, bits [15:8] as Cb component and bits [31:16] must be zero.
> >
> > ctrl->val should therefore be setting dev->colourfx.u and
> > dev->colourfx.v with those masks. dev->colourfx.enable field should
> > have been set when going through ctrl_set_image_effect for contol
> > V4L2_CID_COLORFX set to V4L2_COLORFX_SET_CBCR.
> >
> > I've confirmed with qv4l2 that that is what is wrong. That's only been
> > lurking there for almost 5 years - shows how often these weirder
> > effects get used.
> > I don't mind whether Colin's patch gets merged and then fixed up, or
> > drop Colin's patch and apply the correct logic via a new patch.
>
> no this patch shouldn't be applied. Does it mean you want to send the proper one?

Want to - not really. Ought to - I guess so.
I've got a bunch of checkpatch and other fixes to come too, so once
I've got a mainline kernel build back up and running I'll roll them
all up and blitz the list.

  Dave