Hello Hans, Thank you for the comments. On Mon, Mar 2, 2015 at 3:55 PM, Hans de Goede <hdego...@redhat.com> wrote:
> Hi, > > On 01-03-15 19:42, Vishnu Patekar wrote: > >> Allwinner A33 tablets comes with the libdram binary, fortunately I've >> found the libdram code at >> https://github.com/realthunder/a33_bootloader/ >> tree/master/basic_loader/bsp/bsp_for_a67. >> > > Ah, that is both good and bad... Now, for me good part is over, now it's just bad. > > > I've integrated it with mainline u-boot, still lot to do to post it to >> upstream >> > > Integrated sounds as if you've copied pieces of code from the bsp code > you've found > into mainline u-boot. That is a big no no (this the bad part). AFAIK the > bsp code > does not come with a GPL license header, and Allwinner does not want to > release > these bits under the GPL for whatever reasons, a lot can be said about > this, but > in the end currently the bsp code is not GPL licensed, so we cannot use it > / copy > from it. There can be no discussion on this, when you're submitting this > upstream > you must not have any literal copied code in the patch you're sending > upstream. > > You can use non copyrightable information from the bsp sources like > register > names and the initialization algorithm (IANAL), but you must 100% write > your own > code! > > I've been working on A33 dram support too, without any source code access, > instead > I've been tracing what the boot0 machine code does and going from there. > What I've > sofar is that the code first inits the DRAM PLL / cmu dram registers, it > seems that > the A33 has 2 dram pll-s and that one of the dram_para fields configures > which pll > to use and configures some sigma-delta pattern to reduce rf interference, > at least > on my A33 tablet the code seems to want to pick the new / second dram pll. > But I > see no reason why the first one should not work, so for now if I were you > I would > just use the A23 dram pll / cmu setup code modified to set the one or 2 > extra > reset / enable bits the A33 has, but still using the old / first dram pll, > we can > always add support for the new one later. > > Then the boot0 code calculates a load of timing parameters and writes > these to > registers. I've already written my own C-code reproducing the init > algorithm from > boot0 for this (attached) this is GPL code and you should be able to use > this to > replace a chunk of the bsp code. Note that I found 2 code paths based on a > tpr13 > bit (iirc) one for autoconfig, and one for reading values from the tpr > dram_para > values, my code supports only autoconfig, you can add a printf to warn if > manual > config is requested and still keep using autoconfig. The same goes for any > other > code paths were there is both a manual and an auto option, look at what > actual > shipped tablets are using, only support that and print a warning for the > other > case, were possible always use autoconfig. > > After this boot0 does more stuff, but this is as far as I've gotten and > currently I've other priorities. > > If I were you I would start with the existing dram_sun6i.c from > upstream u-boot, as the A33 DRAM controller seems to be closest to the > A31 one, then add in the dram_sun8i.c pll init code, and the timing > stuff which I've already written, and then see where the initialization > algorithm is different for the A33 and modify the dram_sun6i.c code to > match what is needed to get the A33 going, if extra code is needed you > MUST write NEW code. > > When you submit support for this upstream you must include a Signed-off-by, > and thereby you are declaring that the code is all your own and that you've > the right to submit this code under the GPL license, this means that there > must be absolutely no copied code in your upstream patch submission! > > Also see: > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/ > linux.git/tree/Documentation/SubmittingPatches > > Section "11) Sign your work > > Basic A33 support including dram init available in my personal repo >> https://github.com/vishnupatekar/u-boot-sunxi/tree/a33-dram >> >> I could able to boot u-boot over fel, and get u-boot command prompt on >> microSD pins which are multiplexed with UART0. >> >> The device page for A33 tablet which I've is here: >> http://linux-sunxi.org/Softwinner_astar-rda >> > > Thanks for your work on this, and sorry if I sound a bit harsh above, but I > really need to be strict about not allowing any non GPL code into u-boot. > No, You've not been harsh, instead you've been helpful in this case. Thank you for clearing my doubts. I was under impression that if we keep the copyright header, it can be accepted. BTW, libdram as binary and used in u-boot is also GPL violation, right? I'll see how can I re-use the A31 dram init code and get it work for A33. > > Regards, > > Hans > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
