Received-SPF: pass (google.com: domain of linux-kernel+bounces-167613-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Precedence: bulk
MIME-Version: 1.0
References: <20240429-fix-cocci-v3-0-3c4865f5a4b0@chromium.org>
 <20240429-fix-cocci-v3-26-3c4865f5a4b0@chromium.org> <20240503112758.763d8d31@sal.lan>
 <c4287024-8012-458d-9829-15ffbceb25cf@moroto.mountain>
In-Reply-To: <c4287024-8012-458d-9829-15ffbceb25cf@moroto.mountain>
From: Ricardo Ribalda <ribalda@chromium.org>
Date: Fri, 3 May 2024 13:56:44 +0200
Message-ID: <CANiDSCsU+jgYkUmHZOC8xPsL2DbgU7_sWrby1bQAXQNnp+g6Bg@mail.gmail.com>
Subject: Re: [PATCH v3 26/26] media: dvb-frontends: tda10048: Make the range
 of z explicit.
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>, Martin Tuma <martin.tuma@digiteqautomotive.com>, 
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>, 
	Hugues Fruchet <hugues.fruchet@foss.st.com>, Alain Volmat <alain.volmat@foss.st.com>, 
	Maxime Coquelin <mcoquelin.stm32@gmail.com>, Alexandre Torgue <alexandre.torgue@foss.st.com>, 
	Paul Kocialkowski <paul.kocialkowski@bootlin.com>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Chen-Yu Tsai <wens@csie.org>, 
	Jernej Skrabec <jernej.skrabec@gmail.com>, Samuel Holland <samuel@sholland.org>, 
	Sakari Ailus <sakari.ailus@linux.intel.com>, Thierry Reding <thierry.reding@gmail.com>, 
	Jonathan Hunter <jonathanh@nvidia.com>, Sowjanya Komatineni <skomatineni@nvidia.com>, 
	Luca Ceresoli <luca.ceresoli@bootlin.com>, Matthias Brugger <matthias.bgg@gmail.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, Hans Verkuil <hverkuil@xs4all.nl>, 
	Sergey Kozlov <serjk@netup.ru>, Abylay Ospan <aospan@netup.ru>, 
	Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>, Dmitry Osipenko <digetx@gmail.com>, 
	Benjamin Mugnier <benjamin.mugnier@foss.st.com>, 
	Sylvain Petinot <sylvain.petinot@foss.st.com>, 
	Stanimir Varbanov <stanimir.k.varbanov@gmail.com>, Vikash Garodia <quic_vgarodia@quicinc.com>, 
	"Bryan O'Donoghue" <bryan.odonoghue@linaro.org>, Bjorn Andersson <andersson@kernel.org>, 
	Konrad Dybcio <konrad.dybcio@linaro.org>, linux-media@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, 
	linux-arm-kernel@lists.infradead.org, linux-staging@lists.linux.dev, 
	linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, 
	linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

I am trying to get the DS, but
https://www.nxp.com/acrobat_download/literature/9397/75015931.pdf is a
dead links now.

Anyone have access to the datasheet?

Thanks!

On Fri, 3 May 2024 at 13:55, Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> On Fri, May 03, 2024 at 11:27:58AM +0100, Mauro Carvalho Chehab wrote:
> > Em Mon, 29 Apr 2024 15:05:05 +0000
> > Ricardo Ribalda <ribalda@chromium.org> escreveu:
> >
> > > We do not expect the sample_freq to be over 613MHz.
> > >
> > > Found by cocci:
> > > drivers/media/dvb-frontends/tda10048.c:345:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead.
> > >
> > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > ---
> > >  drivers/media/dvb-frontends/tda10048.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/dvb-frontends/tda10048.c b/drivers/media/dvb-frontends/tda10048.c
> > > index 3e725cdcc66b..1886f733dbbf 100644
> > > --- a/drivers/media/dvb-frontends/tda10048.c
> > > +++ b/drivers/media/dvb-frontends/tda10048.c
> > > @@ -328,7 +328,8 @@ static int tda10048_set_wref(struct dvb_frontend *fe, u32 sample_freq_hz,
> > >                          u32 bw)
> > >  {
> > >     struct tda10048_state *state = fe->demodulator_priv;
> > > -   u64 t, z;
> > > +   u32 z;
> > > +   u64 t;
> > >
> > >     dprintk(1, "%s()\n", __func__);
> > >
> > > @@ -341,6 +342,7 @@ static int tda10048_set_wref(struct dvb_frontend *fe, u32 sample_freq_hz,
> > >     /* t *= 2147483648 on 32bit platforms */
> > >     t *= (2048 * 1024);
> > >     t *= 1024;
> > > +   /* Sample frequency is under 613MHz */
> >
> > Are you sure about that? Some DVB devices have very high frequency
> > clocks, specially if they're also used for satellite, so I can't
> > be sure by just looking at the driver's code.
> >
> > Also, we had already a bunch of regressions with "fixes" like this
> > that actually broke frontend drivers.
>
> This patch preserves the existing behavior. The sample_freq_hz variable
> is a u32 so, in the original code, z couldn't have been more than
> U32_MAX even though it was declared as a u64.
>
> It's possible that the original code was wrong.  We have seen that in
> other places in this patchset.  Adding a note about the datasheet is
> also a good idea.
>
> regards,
> dan carpenter
>


-- 
Ricardo Ribalda