Messages in this thread | | | Date | Wed, 13 Oct 2021 22:55:58 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH v1 12/16] pinctrl: starfive: Add pinctrl driver for StarFive SoCs |
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On Wed, Oct 13, 2021 at 06:38:14PM +0200, Emil Renner Berthing wrote: > On Tue, 12 Oct 2021 at 19:03, Andy Shevchenko <andy.shevchenko@gmail.com> wrote: > > On Tue, Oct 12, 2021 at 4:43 PM Emil Renner Berthing <kernel@esmil.dk> wrote:
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> > > +free_pinmux: > > > + devm_kfree(dev, pinmux); > > > +free_pins: > > > + devm_kfree(dev, pins); > > > +free_grpname: > > > + devm_kfree(dev, grpname); > > > > What the heck?! > > Just to be clear. You mean we don't need to explicitly free them > because they're tied to the device right? I don't think the device > will go away just because a single device tree entry can't be parsed, > so on such errors this garbage would be left behind. You can still > argue we shouldn't optimize for broken device trees, I just want to > make it at conscious decision.
If you are using devm_kfree() it is quite likely shows either of the following issues:
* you mustn't use devm_*() in the first place due to object lifetime; * you shouldn't use devm_kfree() since this is the whole point of devm.
> > > +free_pgnames: > > > + devm_kfree(dev, pgnames); > > > > Ditto.
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> > > +out: > > > > Useless label. > > Hmm.. my compiler disagrees.
The comment implies that you return directly instead of using `goto out;`.
> > > + return ret;
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> > > + v = pinmux[i]; > > > + dout = ((v & BIT(7)) << (31 - 7)) | ((v >> 24) & 0xffU); > > > + doen = ((v & BIT(6)) << (31 - 6)) | ((v >> 16) & 0xffU); > > > + din = (v >> 8) & 0xffU; > > > > What is this voodoo for? > > In order to do pinmux we need the following pieces of information from > the device tree for each pin ("GPIO" they call it): > > output signal: 0-133 + 1bit reverse flag > output enable signal: 0-133 + 1bit reverse flag > optional input signal: 0-74 + special "none" value, right now 0xff > gpio number: 0-63 > > As the code is now all that info is packed into a u32 for each pin > using the GPIOMUX macro defined in the dt-binding header added in > patch 10. There is also a diagram for how this packing is done. The > above voodoo is for unpacking that. > > I'd very much like to hear if you have a better solution for how to > convey that information from the device tree to here.
At very least this code should have something like above in the comment.
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> > > + if (din != 0xff) > > > + reg_din = sfp->base + GPIO_IN_OFFSET + 4 * din; > > > + else > > > + reg_din = NULL; > > > > This looks like you maybe use gpio-regmap instead? > > This was discussed at length when Drew sent in the GPIO part of this code: > https://lore.kernel.org/linux-riscv/20210701002037.912625-1-drew@beagleboard.org/ > The conclusion was that because pinmux and controlling the pins from > software in GPIO mode uses the same registers it is better to do a > combined driver like this that can share the lock among other things.
And what does prevent exactly to base the GPIO part on gpio-regmap?
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> > > +static const unsigned char starfive_drive_strength[] = { > > > + 14, 21, 28, 35, 42, 49, 56, 63, > > > > Why table? Can you simply use the formula?! > > Heh, yeah. So these are rounded values from a table and I never > noticed that after rounding they follow a nice arithmetic progression. > It'll probably still be nice to have an explanation in the comments > about the formula then.
Yup!
> > > +};
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> > > + irq_set_handler_locked(d, handle_bad_irq); > > > > Why is this here? Move it to ->probe(). > > My thinking was that if something tries to set a an unsupported irq > type, we should make sure the caller doesn't get spurious interrupts > because we left the handler at its old value.
You already assigned to this handler in the ->probe(), what's this then?
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> > > + if (value <= 6) > > > + writel(value, sfp->padctl + IO_PADSHARE_SEL); > > > + else > > > > > + dev_err(dev, "invalid signal group %u\n", value); > > > > Why _err if you not bail out here? > > My thinking was that if the device tree specifies an invalid signal > group we should just leave the setting alone and not break booting, > but still be loud about it. Maybe that's too lenient and it's better > to crash and burn immediately if someone does that.
Here is inconsistency between level of the message and following action. There are (rare!) cases when it's justified, but I believe it's not the case here. You have two choices or justify why you have to use error level without stopping process.
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All uncommented stuff you agreed on, correct?
-- With Best Regards, Andy Shevchenko
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