From: Johan Hovold <email@example.com> To: Linus Walleij <firstname.lastname@example.org> Cc: Johan Hovold <email@example.com>, Marc Zyngier <firstname.lastname@example.org>, linux-usb <email@example.com>, "open list:GPIO SUBSYSTEM" <firstname.lastname@example.org>, "email@example.com" <firstname.lastname@example.org>, Bartosz Golaszewski <email@example.com>, Greg Kroah-Hartman <firstname.lastname@example.org>, email@example.com Subject: Re: [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity Date: Wed, 9 Dec 2020 18:05:58 +0100 [thread overview] Message-ID: <X9ED9k5gxIlQ0YJ/@localhost> (raw) In-Reply-To: <CACRpkda+JJ9ZMmwPcA_Rc0tgqKQw+VTgfVyp8PsZG55VM82uzg@mail.gmail.com> On Wed, Dec 09, 2020 at 10:35:53AM +0100, Linus Walleij wrote: > On Mon, Dec 7, 2020 at 4:19 PM Johan Hovold <firstname.lastname@example.org> wrote: > > On Mon, Dec 07, 2020 at 03:00:37PM +0000, Marc Zyngier wrote: > > > On 2020-12-07 14:29, Johan Hovold wrote: > > > > On Fri, Dec 04, 2020 at 04:47:38PM +0000, Marc Zyngier wrote: > > > > > >> + if (!bitmap_full(valid_mask, ngpios)) > > > >> + dev_warn_once(&port->dev, "Consider using a tool such as ftx-prog > > > >> to enable GPIOs if required\n"); > > > >> + > > > > > > > > And again, this is not something that belongs in the logs of just about > > > > every system with an attached ftdi device. > > > > > > Fine by me, this patch can be dropped without issue. After all, > > > I now know how to deal with these chips. > > > > > > > While not possible to combine with the valid_mask approach, this is > > > > something which we could otherwise add to the request() callback for > > > > the > > > > first request that fails due to the mux configuration. > > > > > > That was Linus' initial suggestion. But I think a consistent user > > > API is more important than free advise in the kernel log. > > > > I tend to agree. So since your valid-mask approach clearly has some > > merit in that it marks the lines in use when using the new cdev > > interface, perhaps we should stick with that. > > It sounds like we agree that this patch sans prints is acceptable. > > It makes things better so let's go with that. Sounds good. I'm about to apply patches 2, 3 and 4 with some smaller changes like demoting the printk messages to KERN_DEBUG and dropping the ftx-progs warning. > The problem for the user is that the line looks to be > "used by the kernel" (true in some sense) but they have no > idea what to do about it and that the ftx-prog will solve > their hacking problem. Right, it's not ideal, but the datasheets for these devices clearly states that the configuration of the CBUS pins is done in EEPROM and the vendor provides some tool to do that. Then there's a bunch of open source implementations for the same including ftx-progs (which can only be used for a subset of these devices). I'd be fine with a dev_err() on the first request that fails saying that the CBUS pin is not configured for GPIO use (perhaps even on every request if its not something that a non-root user can trigger). But we cannot have both that and have the line marked in-use through the chardev interface currently. I'm admittedly a bit torn on which is preferable. Johan
next prev parent reply other threads:[~2020-12-09 17:06 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-04 16:47 [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Marc Zyngier 2020-12-04 16:47 ` [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used Marc Zyngier 2020-12-07 14:16 ` Johan Hovold 2020-12-07 14:59 ` Marc Zyngier 2020-12-09 9:25 ` Linus Walleij 2020-12-04 16:47 ` [PATCH 2/4] USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib Marc Zyngier 2020-12-09 9:28 ` Linus Walleij 2020-12-04 16:47 ` [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity Marc Zyngier 2020-12-07 14:29 ` Johan Hovold 2020-12-07 15:00 ` Marc Zyngier 2020-12-07 15:19 ` Johan Hovold 2020-12-09 9:35 ` Linus Walleij 2020-12-09 17:05 ` Johan Hovold [this message] 2020-12-09 17:39 ` Johan Hovold 2020-12-04 16:47 ` [PATCH 4/4] USB: serial: ftdi_sio: Drop GPIO line checking dead code Marc Zyngier 2020-12-07 9:55 ` [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Andy Shevchenko 2020-12-07 14:01 ` Johan Hovold 2020-12-07 14:41 ` Marc Zyngier 2020-12-07 15:08 ` Johan Hovold 2020-12-07 15:34 ` Marc Zyngier 2020-12-07 15:49 ` Johan Hovold 2020-12-09 9:20 ` Linus Walleij 2020-12-09 15:42 ` Johan Hovold
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