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 -- 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
