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Message-ID: <Y+9j3cYOG+Z0zmyC@smile.fi.intel.com>
Date: Fri, 17 Feb 2023 13:24:13 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: linux-media@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Wolfram Sang <wsa@...nel.org>,
Luca Ceresoli <luca.ceresoli@...tlin.com>,
Matti Vaittinen <Matti.Vaittinen@...rohmeurope.com>,
Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Peter Rosin <peda@...ntia.se>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Michael Tretter <m.tretter@...gutronix.de>,
Shawn Tu <shawnx.tu@...el.com>,
Hans Verkuil <hverkuil@...all.nl>,
Mike Pagano <mpagano@...too.org>,
Krzysztof Hałasa <khalasa@...p.pl>,
Marek Vasut <marex@...x.de>,
Satish Nagireddy <satish.nagireddy@...cruise.com>
Subject: Re: [PATCH v9 0/8] i2c-atr and FPDLink
On Fri, Feb 17, 2023 at 08:57:32AM +0200, Tomi Valkeinen wrote:
> On 16/02/2023 17:53, Andy Shevchenko wrote:
> > On Thu, Feb 16, 2023 at 04:07:39PM +0200, Tomi Valkeinen wrote:
...
> > > struct i2c_board_info ser_info = {
> > > - .of_node = to_of_node(rxport->remote_fwnode),
> > > - .fwnode = rxport->remote_fwnode,
> >
> > > + .of_node = to_of_node(rxport->ser.fwnode),
> > > + .fwnode = rxport->ser.fwnode,
> >
> > Why do you need to have both?!
>
> I didn't debug it, but having only fwnode there will break the probing (no
> match).
This needs to be investigated. The whole fwnode approach, when we have both
fwnode and legacy of_node fields in the same data structure, is that fwnode
_OR_ of_node initialization is enough, when both are defined the fwnode
should take precedence.
If your testing is correct (and I have no doubts) it means we have a serious
bug lurking somewhere.
> > > .platform_data = ser_pdata,
> > > };
...
> > cur_vc = desc.entry[0].bus.csi2.vc;
> >
> > > + for (i = 0; i < desc.num_entries; ++i) {
> > > + u8 vc = desc.entry[i].bus.csi2.vc;
> >
> > > + if (i == 0) {
> > > + cur_vc = vc;
> > > + continue;
> > > + }
> >
> > This is an invariant to the loop, see above.
>
> Well, the current code handles the case of num_entries == 0. I can change it
> as you suggest, and first check if num_entries == 0 and also start the loop
> from 1.
You may try to compile both variants and see which one gets lets code.
I believe it will be mine or they are equivalent in case compiler is clever
enough to recognize the invariant.
> > > + if (vc == cur_vc)
> > > + continue;
> > > +
> > > + dev_err(&priv->client->dev,
> > > + "rx%u: source with multiple virtual-channels is not supported\n",
> > > + nport);
> > > + return -ENODEV;
> > > + }
...
> > > + for (i = 0; i < 6; ++i)
> > > ub960_read(priv, UB960_SR_FPD3_RX_ID(i), &id[i]);
> > > id[6] = 0;
> >
> > Wondering if this magic can be defined.
>
> The number of ID registers? Yes, I can add a define.
Yes.
...
...
> > > if (ret) {
> > > if (ret != -EINVAL) {
> > > - dev_err(dev,
> > > - "rx%u: failed to read 'ti,strobe-pos': %d\n",
> > > - nport, ret);
> > > + dev_err(dev, "rx%u: failed to read '%s': %d\n", nport,
> > > + "ti,strobe-pos", ret);
> > > return ret;
> > > }
> > > } else if (strobe_pos < UB960_MIN_MANUAL_STROBE_POS ||
> > > @@ -3512,8 +3403,8 @@ ub960_parse_dt_rxport_link_properties(struct ub960_data *priv,
> > > ret = fwnode_property_read_u32(link_fwnode, "ti,eq-level", &eq_level);
> > > if (ret) {
> > > if (ret != -EINVAL) {
> > > - dev_err(dev, "rx%u: failed to read 'ti,eq-level': %d\n",
> > > - nport, ret);
> > > + dev_err(dev, "rx%u: failed to read '%s': %d\n", nport,
> > > + "ti,eq-level", ret);
> > > return ret;
> > > }
> > > } else if (eq_level > UB960_MAX_EQ_LEVEL) {
> >
>
> Hmm, I noticed this one (and the one above) was missing return -EINVAL.
>
> > Seems like you may do (in both cases) similar to the above:
> >
> > var = 0;
> > ret = read_u32();
> > if (ret && ret != -EINVAL) {
> > // error handling
> > }
> > if (var > limit) {
> > // another error handling
> > }
>
> That's not the same. You'd also need to do:
>
> if (!ret) {
> // handle the retrieved value
> }
>
> which, I think, is not any clearer (perhaps more unclear).
>
> What I could do is:
>
> if (ret) {
> if (ret != -EINVAL) {
> dev_err(dev, "rx%u: failed to read '%s': %d\n", nport,
> "ti,eq-level", ret);
> return ret;
> }
> } else {
> if (eq_level > UB960_MAX_EQ_LEVEL) {
> dev_err(dev, "rx%u: illegal 'ti,eq-level' value: %d\n",
> nport, eq_level);
> return -EINVAL;
> }
>
> rxport->eq.manual_eq = true;
> rxport->eq.manual.eq_level = eq_level;
> }
>
> Maybe the above style makes it clearer, as it clearly splits the "don't have
> value" and "have value" branches.
Up to you, but this just a good example why I do not like how optional
properties are handled in a "smart" way.
To me
foo = DEFAULT;
_property_read_(&foo); // no error checking
is clean, neat, small and good enough solution.
...
> > > + static const char *vpoc_names[UB960_MAX_RX_NPORTS] = { "vpoc0", "vpoc1",
> > > + "vpoc2", "vpoc3" };
> >
> > Wouldn't be better to format it as
> >
> > static const char *vpoc_names[UB960_MAX_RX_NPORTS] = {
> > "vpoc0", "vpoc1", "vpoc2", "vpoc3",
> > };
> >
> > ?
>
> Clang-format disagrees, but I agree with you ;).
So it needs to be fixed then :-)
Glad that you agreed on this.
--
With Best Regards,
Andy Shevchenko
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