Hi Rob, On Fri, Feb 20, 2015 at 11:30:12AM -0600, Rob Herring 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. > > Rob It is acualyy what we did but we are not happy with this solution because as said previously we rely on U-Boot and on dts/dtsi side we have too many files. Regards Ludovic -- 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
