Re: [PATCH v9 0/8] i2c-atr and FPDLink
From: Tomi Valkeinen
Date: Fri Feb 17 2023 - 07:57:49 EST
On 17/02/2023 13:24, Andy Shevchenko wrote:
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.
Having both defined or only of_node defined works for me.
Perhaps the issue is that these drivers only add of_match_table, and
thus having only .fwnode above is not enough.
Looking at i2c_device_match(), i2c_of_match_device() only uses of_node,
so perhaps I would need CONFIG_ACPI for acpi_driver_match_device to do
matching with of_node? Although I don't see the acpi code using fwnode,
just of_node. Well, I have to say I have no idea without spending more
time on this.
.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.
But your suggestion accesses desc.entry[0] even if there are no entries,
accessing possibly uninitialized memory. In that case it doesn't use it
for anything, but at least I find that kind of code worrying.
+ 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.
Yes, if you have a default. I don't. I could add a new magic number for
the eq_level which means not-defined and use it as a default, but I
don't usually like default values which are not 0. Here I have the
manual_eq boolean to tell if we're using manual EQ or not.
Tomi