From mboxrd@z Thu Jan 1 00:00:00 1970 From: Liviu.Dudau@arm.com (Liviu Dudau) Date: Mon, 9 Mar 2015 10:12:05 +0000 Subject: [PATCH 1/2] arm64: juno: Add APB registers and LEDs using syscon In-Reply-To: References: <1424866589-2988-1-git-send-email-linus.walleij@linaro.org> <20150225135512.GE12377@arm.com> <20150225144756.GA905@e106497-lin.cambridge.arm.com> <20150225150023.GJ12377@arm.com> <20150225151157.GC905@e106497-lin.cambridge.arm.com> <20150227140600.GZ905@e106497-lin.cambridge.arm.com> Message-ID: <20150309101205.GY16268@e106497-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Mar 07, 2015 at 10:24:08PM +0000, Linus Walleij wrote: > On Fri, Feb 27, 2015 at 3:06 PM, Liviu Dudau wrote: > > On Fri, Feb 27, 2015 at 01:07:42PM +0000, Linus Walleij wrote: > > >> Notice that the SD card slot is *ALSO* inside the box, do you mean we > >> should then also delete the uSD card support added in > >> commit 71f867ec130e3cc8e692366fdf8941ded27c727e > >> by yourself because the SD card slot is not reachable? > >> Notice that to access that card slot you even have to remove the > >> nice blue ARM boilerplate. > > > > That's not my view. I have a mobile phone with an uSD card slot, but I have to take > > the cover off (and the battery) to access it. It doesn't mean I should not be able > > to use it from kernel side because of that, only that the designer of the phone > > (and of the Juno board + box by extension) did not expect people to use it with > > covers off all the time. > > > > > > I fail to see why you need to remove the SD card all the time. Surely opening > > the case once to put the uSD card in is enough? ;) > > > > > >> > >> The board is obviously designed to be reachable and the top part > >> of the case is obviously designed to be taken off by professional > >> users. > > > > I'm mostly on your side, Linus, I was just looking for more use cases. Like I've said, > > most of our customers seem to keep the case closed (or at least that is what they tell > > us :) ) so I'm looking for explanations on how you use the LEDs (visual debugging for > > big-LITTLE was how Lorenzo was using them on TC2 for example). Linus, > > OK now I feel bad and maybe I was not in such a good mood that day. Don't worry, I actually found it amusing. > > The LEDs I added are really useful on the other ARM reference designs, > the heartbeat gives a sign that the system is alive even if your console is > not working and that's what I appreaciate a lot about it (the > heartbeat intensity > also indicates system load). > > The MMC read/write LED is as useful as the hard disk activity LED on > some older PCs, kinda nice if you want to know something is going on. > > The rest of the LEDs show which CPU cores are active. This was the > original use of the LEDs on the RealView PB11MPcore and it was > appreciated by the multicore developers who could see the different > CPUs being busy with tasks. In that case you might want to use the remaining 2 leds for cpus 4 and 5, as Juno has a total of 6 cores. Your current patch leaves two LEDs unassigned. > > LEDs on development boards are real nice, simply, and I think also > some deployed ARM64 server systems will have them. Agree on LEDs being nice. I'm guessing that on server side if you want blinking lights you need ACPI? ;) Best regards, Liviu > > Yours, > Linus Walleij > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ?\_(?)_/?