Hi Rob, > On Feb 20, 2015, at 19:30 , Rob Herring <robherring2@xxxxxxxxx> wrote: > > On Fri, Feb 20, 2015 at 8:35 AM, Ludovic Desroches > <ludovic.desroches@xxxxxxxxx> wrote: >> On Fri, Feb 20, 2015 at 09:21:38AM -0500, Peter Hurley wrote: >>> On 02/19/2015 12:38 PM, Pantelis Antoniou wrote: >>>> >>>>> On Feb 19, 2015, at 19:30 , Frank Rowand <frowand.list@xxxxxxxxx> wrote: >>>>> >>>>> On 2/19/2015 9:00 AM, Pantelis Antoniou wrote: >>>>>> Hi Frank, > > [...] > >>>>>> This is one of those things that the kernel community doesn’t understand which makes people >>>>>> who push product quite mad. >>>>>> >>>>>> Engineering a product is not only about meeting customer spec, in order to turn a profit >>>>>> the whole endeavor must be engineered as well for manufacturability. >>>>>> >>>>>> Yes, you can always manually install files in the bootloader. For 1 board no problem. >>>>>> For 10 doable. For 100 I guess you can hire an extra guy. For 1 million? Guess what, >>>>>> instead of turning a profit you’re losing money if you only have a few cents of profit >>>>>> per unit. >>>>> >>>>> I'm not installing physical components manually. Why would I be installing software >>>>> manually? (rhetorical question) >>>>> >>>> >>>> Because on high volume product runs the flash comes preprogrammed and is soldered as is. >>>> >>>> Having a single binary to flash to every revision of the board makes logistics considerably >>>> easier. >>>> >>>> Having to boot and tweak the bootloader settings to select the correct dtb (even if it’s present >>>> on the flash medium) takes time and is error-prone. >>>> >>>> Factory time == money, errors == money. >>>> >>>>>> >>>>>> No knobs to tweak means no knobs to break. And a broken knob can have pretty bad consequences >>>>>> for a few million units. >>>>> >>>>> And you produce a few million units before testing that the first one off the line works? >>>>> >>>> >>>> The first one off the line works. The rest will get some burn in and functional testing if you’re >>>> lucky. In many cases where the product is very cheap it might make financial sense to just ship >>>> as is and deal with recalls, if you’re reasonably happy after a little bit of statistical sampling. >>>> >>>> Hardware is hard :) >>> >>> I'm failing to see how this series improves your manufacturing process at all. >>> >>> 1. Won't you have to provide the factory with different eeprom images for the >>> White and Black? You _trust_ them to get that right, or more likely, you >>> have process control procedures in place so that you don't get 1 million Blacks >>> flashed with the White eeprom image. >>> >>> 2. The White and Black use different memory technology so it's not as if the >>> eMMC from the Black will end up on the White SMT line (or vice versa). >>> >>> 3 For that matter, why wouldn't you worry that all the microSD cards intended >>> for the White were accidentally assembled with the first 50,000 Blacks; at >>> that point you're losing a lot more than a few cents of profit. And that has >>> nothing to do with what image you provided. >>> >> >> As you said, we can imagine many reasons to have a failure during the >> production, having several DTB files will increase the risk. > > Then package them as a single file. You can even use DT to do that. > See u-boot FIT image. > In the ideal case there is no u-boot, and no bootloader. Packaging 27 difference DTBs, as in the Atmel people case, differing in only a few properties seems a waste of space, no? We keep on dancing around the issue, namely that DT does not have a quirk/variant mechanism. I feel that it is a glaring omission. We can’t keep shoveling crap over the fence to firmware and expect it to get buried there. > Rob Regards — Pantelis -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
