Hi, Geert, On 4/3/23 17:29, Geert Uytterhoeven wrote: > On Tue, Mar 21, 2023 at 4:01 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: >> On Mon, Mar 20, 2023 at 7:57 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: >>> On Mon, Mar 20, 2023 at 6:04 PM Tudor Ambarus <tudor.ambarus@xxxxxxxxxx> wrote: >>>> Vignesh used to review CFI code, maybe he can intervene. I've never >>>> worked with CFI, but I can try to help. I'll need more debug data though. >>>> >>>> On 3/20/23 16:43, Geert Uytterhoeven wrote: >>>>> Add a device node for the Spansion S29GL512N NOR FLASH on the Marzen >>>>> development board. >>>>> >>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> >>>>> --- >>>>> Although the S29GL512N is a CFI FLASH, using "cfi-flash" instead of >>>>> "mtd-rom" does not work: >>>>> 1. Probing fails with "physmap-flash 0.flash: map_probe failed", >>>> >>>> I would first try to understand why the probe fails. > >> I suddenly remembered I have a different board (APE6-EVM), where >> the CFI-FLASH stopped working after adding support for secondary >> CPUs. I always thought that was a hardware quirk... >> >> Turns out the CFI-FLASH on Marzen (quad Cortex-A9) is detected when >> booting with "nosmp": > >> My first guess was that the probing process is migrated to a different >> CPU core during probing, but printing smp_processor_id() didn't >> confirm that; it's just running on a different CPU core than CPU0. >> Wrapping the body of cfi_qry_mode_on() inside a get_cpu()/put_cpu() >> pair to prevent migration also didn't fix it. >> >> Is CFI-FLASH known-broken on SMP? > > After actively looking for more boards with CFI FLASHes, and finding one > more board where FLASH probing fails on SMP, I dug deeper. > Turns out they all have in common that (a) the CFI FLASH is located at > physical address zero, and (b) the secondary CPU bringup code relies > on mapping (by special hardware) the region at address zero to the > CPU boot code... > > Hence fixing this involves making sure that accessing FLASH and bringing > CPU cores online do not happen concurrently... > Would deferring probe for CFI work? ta
