On 11/21/19 10:59 AM, Tan, Ley Foon wrote: [...] Hi,
>> Subject: [PATCH 2/2] ARM: socfpga: Purge pending transactions upon >> enabling bridges on Gen5 >> >> On Gen5, when the FPGA is loaded and there was some prior interaction >> between the HPS and the FPGA via bridges (e.g. Linux was running and using >> some of the IPs in the FPGA) followed by warm reset, it has been observed >> that there might be outstanding unfinished transactions. This leads to an >> obscure misbehavior of the bridge. >> >> When the bridge is enabled again in U-Boot and there are outstanding >> transactions, a read from within the bridge address range would return a >> result of the previous read instead. Example: >> => bridge enable ; md 0xff200000 1 >> ff200000: 1234abcd >> => bridge enable ; md 0xff200010 1 >> ff200010: 5678dcba <------- this is in fact a value which is stored in >> a memory at 0xff200000 => bridge enable ; md >> 0xff200000 1 >> ff200000: 90effe09 <------- this is in fact a value which is stored in >> a memory at 0xff200010 and so it continues. >> Issuing a write >> does lock the system up completely. >> >> This patch opens the FPGA bridges in 'bridge enable' command, the tears >> them down again, and then opens them again. This allows these outstanding >> transactions to complete and makes this misbehavior go away. >> >> However, it is not entirely clear whether this is the correct solution. >> >> Signed-off-by: Marek Vasut <ma...@denx.de> >> Cc: Chin Liang See <chin.liang....@intel.com> >> Cc: Dalon Westergreen <dwest...@gmail.com> >> Cc: Dinh Nguyen <dingu...@kernel.org> >> Cc: Ley Foon Tan <ley.foon....@intel.com> >> Cc: Simon Goldschmidt <simon.k.r.goldschm...@gmail.com> >> Cc: Tien Fong Chee <tien.fong.c...@intel.com> > > Reviewed-by: Ley Foon Tan <ley.foon....@intel.com> Do you think there is anyone still at Altera/intel who might be able to tell us what this problem really is about ? And whether there is some way to purge those stuck transactions without turning the bridges on and off and then on again ? Or whether there is a way to even verify there are stuck transactions ? -- Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
