On Mon, Sep 29, 2014 at 2:16 PM, Karsten Merker <mer...@debian.org> wrote: > On Mon, Sep 29, 2014 at 09:13:37AM +0300, Siarhei Siamashka wrote: > >> On Sun, 28 Sep 2014 20:13:21 +0200 >> Hans de Goede <hdego...@redhat.com> wrote: >> >> > In order for the gmac nic to work reliable on the Bananapi, we need to poke >> > these 2 undocumented bits in the gmac clk register. Since these are >> > undocumented, this commit only sets these bits on the Bananapi for now. >> > >> > I'll contact Allwinner to try and get these bits documented, once they >> > are documented we can hopefully replace this hack with a better patch. >> >> Could you please provide a bit more details in the commit message? >> What are the symptoms of the problem? > > Without the patch, u-boot on the BananaPi shows massive packet loss > on every network activity. The packet loss is so extreme that it is > actually impossible to boot a kernel by tftp because u-boot gives up. > The mainline kernel has (once booted) shown similar problems on the > BananaPi. > >> How did you come to the idea to poke these bits? > > The linux 3.4 kernel from https://github.com/LeMaker/linux-bananapi > (which is a patched linux-sunxi.org 3.4 kernel) does not show this > problem, so we started looking into what is different there, and the > relevant change that was found was setting these particular > undocumented bits.
File at issue here asking for the documentation https://github.com/allwinner-zh/documents > >> Does the GMAC driver in the linux kernel need a similar >> fix/workaround? > > Not as far as I can see - once u-boot has set these two bits during > system initialization, the mainline kernel works fine without > any changes. > >> Also as mentioned in another e-mail >> http://lists.denx.de/pipermail/u-boot/2014-September/190096.html >> u-boot configures the "912MHz @1.4V" CPU clock frequency/voltage >> setup for sun7i hardware. And according to the information from Tony >> Zhang, this is supposed to be unreliable for the Banana Pi. So what >> happens to this GMAC bug if you just increase the dcdc2 voltage in >> u-boot (or reduce the CPU clock frequency)? > > I can test that if you could tell me what would have to be changed > in u-boot to do that. > > Regards, > Karsten > -- > Gem. Par. 28 Abs. 4 Bundesdatenschutzgesetz widerspreche ich der Nutzung > sowie der Weitergabe meiner personenbezogenen Daten für Zwecke der > Werbung sowie der Markt- oder Meinungsforschung. > > -- > You received this message because you are subscribed to the Google Groups > "linux-sunxi" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to linux-sunxi+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- Jon Smirl jonsm...@gmail.com _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
