From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fTj7n-0003XP-O5 for barebox@lists.infradead.org; Fri, 15 Jun 2018 07:26:31 +0000 Date: Fri, 15 Jun 2018 09:26:09 +0200 From: Sascha Hauer Message-ID: <20180615072608.uo7uwskm4qjfcr76@pengutronix.de> References: <20180615041136.23492-1-andrew.smirnov@gmail.com> <20180615041136.23492-5-andrew.smirnov@gmail.com> <20180615045805.GB10093@ravnborg.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180615045805.GB10093@ravnborg.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 02/27] console: Unify console_simple.c and pbl/console.c To: Sam Ravnborg Cc: Andrey Smirnov , barebox@lists.infradead.org On Fri, Jun 15, 2018 at 06:58:05AM +0200, Sam Ravnborg wrote: > Hi Andrey. > > > + > > +/** > > + * __console_get_default - Return default output console > > + * > > + * Internal function used to determine which console to use for early > > + * output. It has the following two use-cases: > > + * > > + * 1. PBL, where it falls back onto console_ll and whatever it is > > + * set up to (either putc_ll or custome callback set with > > + * pbl_set_putc()) > > + * > > + * 2. CONSOLE_SIMPLE, where it falls back onto console_ll (which in > > + * this case always boils down to a putc_ll() call) until first > > + * (and only) console is registered via console_register(). > > + */ > > +struct console_device *__console_get_default(void) > > If it is used as internal only then it should be static. > (Have not read the the remaining patches) > > > +{ > > + /* > > + * Doing on-demand initialization here as opposed to in the > > + * definition of console_ll above has that advantage that on > > + * some architecutres (e.g. AArch64) it allows us to avoid > > + * additional relocation and makes it possible to use console > > + * infrastructure before any relocation happens > > + */ > > + if (unlikely(!console_ll.putc)) > > + console_ll.putc = __console_ll_putc; > > + > > + if (IS_ENABLED(__PBL__) || !console) > > + return &console_ll; > > + > > + return console; > > +} > > + > > +/** > > + * __console_set_putc - Early console initalization helper > > + * > > + * @cdev: Console device to initialize > > + * @putcf: putc() implementation to be used for this console > > + * @ctx: Context to pass to putc() > > + * > > + * Internal function used to initialize early/trivial console devices > > + * capable of only outputting a single character > > + */ > > +void __console_set_putc(struct console_device *cdev, > > + putc_func_t putcf, void *ctx) > Likewise, and so on for the reimaining __xxx functions. > > > > +{ > > + cdev->putc = (void *)putcf; > > + cdev->ctx = ctx; > > +} > > + > > +/** > > + * __cdev_putc - Internal .putc() callback dispatcher > > + * > > + * @cdev: Console device to use > > + * @c: Character to print > > + * > > + * Internal .putc() callback dispatcher needed to correctly select > > + * which context to pass. > > + * > > + * This is needed becuase when being used in PBL in conjunction with > > + * pbl_set_putc(), .putc() callback is expecting to receive a void * > > + * context that was registered earlier. > > + * > > + * In the "normal" world, however all of the .putc() callback are > > + * written with expectation of receiving struct console_device * as a > > + * first argument. > > + * > > + * Accomodation of both of those use-cases is the purpoese of this > > + * function > > + */ > > +void __cdev_putc(struct console_device *cdev, char c) > > +{ > > + void *ctx = cdev->ctx ? : cdev; > Looks strange to me. > What is ctx assigned in the "true" case? > Maybe there is some subtle C rule that I have missed/forgot. > Point is, if this is valid code it may also make other puzzeled. It's a shortcut for a ? a : b and I like kind of like it. I'm also still not there that I can read fluently over it, but I think it's worth learning it. What puzzles me here is that the putc callback is either passed a context pointer or cdev itself if there is no context. I haven't read the full patch yet, but that is one thing that I don't like. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox