On 3/11/20 10:54 AM, Ley Foon Tan wrote: > On Mon, Mar 9, 2020 at 10:10 PM Simon Goldschmidt > <[email protected]> wrote: >> >> On Mon, Mar 9, 2020 at 1:57 PM Marek Vasut <[email protected]> wrote: >>> > >>>>> >>>> >>>> I can reproduce the issue if without setting applycfg bit. Access to >>>> F2sdram interface will cause system hang. >>>> >>>> From the Cyclone 5 Soc datasheet: >>>> applycfg - Write with this bit set to apply all the settings loaded in >>>> SDR registers to the memory interface. This bit is write-only and >>>> always returns 0 if read. >>>> >>>> Software should set applycfg bit if change any register under SDR >>>> register range. SW is allowed to set this bit multiple times, the only >>>> condition is SDRAM need to be idle. >>>> My suggestion is we add back socfpga_sdram_apply_static_cfg(), but >>>> change the sequence to below: >>>> writel(iswgrp_handoff[3], &sdr_ctrl->fpgaport_rst); >>>> socfpga_sdram_apply_static_cfg(); >>>> >>>> Marek and Simon, are you okay with this? If yes, I will submit patch for >>>> this. >>> >>> The problem was that this was causing weird sporadic hangs on Gen5, >>> which is why it was removed. So until there is an explanation for those >>> hangs, I'm not really OK with this. >> >> These sporadic hangs you saw were on devices without an FPGA image directly >> accessing the SDRAM ports, right? >> >>> >>> Maybe the application of static config should happen in SPL, before the >>> DRAM is running, or something like that ? >> >> Thinking this further, limiting it to applying in SPL is not a good idea >> since >> that prevents us from implementing different FPGA images/configs by loading a >> config later in the boot (i.e. in U-Boot from a FIT-image). >> >> Would it work to make setting this optional, i.e. only write the bit if an >> FPGA >> config actually uses these ports? Then it couldn't lead to problems on other >> hardware... > > If the sporadic hangs issue happen on FPGA image that doesn't connect > to f2sdram interface, we can add the checking to only apply static cfg > when it has f2sdram port enabled. > It can send a patch with this checking for you to try if want. Well, what could cause that sporadic hang ? Yes, the hang happens on image which doesn't access the SDRAM IIRC.
-- Best regards, Marek Vasut
