> -----Original Message----- > From: Marek Vasut <[email protected]> > Sent: Thursday, November 21, 2019 5:35 AM > To: [email protected] > Cc: Marek Vasut <[email protected]>; See, Chin Liang > <[email protected]>; Dalon Westergreen <[email protected]>; > Dinh Nguyen <[email protected]>; Tan, Ley Foon > <[email protected]>; Simon Goldschmidt > <[email protected]>; Chee, Tien Fong > <[email protected]> > 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 <[email protected]> > Cc: Chin Liang See <[email protected]> > Cc: Dalon Westergreen <[email protected]> > Cc: Dinh Nguyen <[email protected]> > Cc: Ley Foon Tan <[email protected]> > Cc: Simon Goldschmidt <[email protected]> > Cc: Tien Fong Chee <[email protected]>
Reviewed-by: Ley Foon Tan <[email protected]> Regards Ley Foon _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
