From 2bb361f0f5151f0cbf0bfcde085c05ca38c42de9 Mon Sep 17 00:00:00 2001 From: Nico Huber Date: Sun, 28 Mar 2021 18:07:00 +0200 Subject: nb/intel/x4x: Refactor sync DLL programming (part 2) Instead of counting consecutive matches (in `j`), check for a second match directly in the control flow. Also, add some dedicated variables: * `tap`: Keeps track of the tap value that resulted in a match and is eventually programmed into the hardware. * `tap2`: Is just temporarily used to search for another edge. Keeping `tap` sync'ed with the hardware has the benefit that we don't need to read the programmed value back for later fixups. Change-Id: I3ae541c39efdc695f5ca74bc757b2f009239ec93 Signed-off-by: Nico Huber Reviewed-on: https://review.coreboot.org/c/coreboot/+/51903 Tested-by: build bot (Jenkins) Reviewed-by: Arthur Heymans --- src/northbridge/intel/x4x/raminit_ddr23.c | 80 +++++++++++++++---------------- 1 file changed, 39 insertions(+), 41 deletions(-) diff --git a/src/northbridge/intel/x4x/raminit_ddr23.c b/src/northbridge/intel/x4x/raminit_ddr23.c index 99c07f597071..2d70b96d5d93 100644 --- a/src/northbridge/intel/x4x/raminit_ddr23.c +++ b/src/northbridge/intel/x4x/raminit_ddr23.c @@ -680,7 +680,7 @@ static bool sync_dll_test_tap(unsigned int tap, uint32_t val) return mchbar_read32(0x184) == val; } -static void sync_dll_search_tap(uint8_t *tap, uint32_t val) +static void sync_dll_search_tap(unsigned int *tap, uint32_t val) { for (; *tap < sync_dll_max_taps; ++*tap) if (sync_dll_test_tap(*tap, val)) @@ -689,7 +689,7 @@ static void sync_dll_search_tap(uint8_t *tap, uint32_t val) static void program_dll(struct sysinfo *s) { - u8 i, j, r, reg8, clk, async = 0; + u8 i, r, reg8, clk, async = 0; u16 reg16 = 0; u32 reg32 = 0; @@ -842,61 +842,59 @@ static void program_dll(struct sysinfo *s) } /* XXX if not async mode */ + unsigned int tap; mchbar_clrbits16(0x180, 1 << 15 | 1 << 9); mchbar_setbits8(0x180, 1 << 2); - j = 0; - for (i = 0; i < sync_dll_max_taps; i++) { - if (sync_dll_test_tap(i, 0xffffffff)) { - j++; - if (j >= 2) - break; + for (tap = 0; tap < sync_dll_max_taps; ++tap) { + sync_dll_search_tap(&tap, 0xffffffff); - if (s->selected_timings.mem_clk == MEM_CLOCK_667MHz) { - j = 2; - break; - } - } else { - j = 0; - } + if (s->selected_timings.mem_clk == MEM_CLOCK_667MHz) + break; + + ++tap; /* other clock speeds need a second match */ + if (sync_dll_test_tap(tap, 0xffffffff)) + break; } - if (i == 1 || ((i == 0) && s->selected_timings.mem_clk == MEM_CLOCK_667MHz)) { - j = 0; - i++; - sync_dll_search_tap(&i, 0); - i++; - for (; i < sync_dll_max_taps; i++) { - if (sync_dll_test_tap(i, 0xffffffff)) { - j++; - if (j >= 2) - break; - } else { - j = 0; - } + + /* look for a real edge if we started with a match */ + if (tap <= 1) { + unsigned int tap2 = tap + 1; + sync_dll_search_tap(&tap2, 0); + + for (++tap2; tap2 < sync_dll_max_taps; ++tap2) { + sync_dll_search_tap(&tap2, 0xffffffff); + + ++tap2; /* we need a second match */ + if (sync_dll_test_tap(tap2, 0xffffffff)) + break; } - if (j < 2) { + + if (tap2 < sync_dll_max_taps) { + tap = tap2; + } else { + /* Using 0 instead of the original `tap` seems + inconsistent, but is what the code always did. */ sync_dll_load_tap(0); - j = 2; + tap = 0; } } - if (j < 2) { + if (tap >= sync_dll_max_taps) { mchbar_clrsetbits8(0x1c8, 0x1f, 0); + tap = 0; async = 1; printk(BIOS_NOTICE, "HMC failed, using async mode\n"); } mchbar_clrbits8(0x180, 1 << 7); - if ((s->spd_type == DDR3 && s->selected_timings.mem_clk == MEM_CLOCK_1066MHz) - || (s->spd_type == DDR2 && s->selected_timings.fsb_clk == FSB_CLOCK_800MHz - && s->selected_timings.mem_clk == MEM_CLOCK_667MHz)) { - i = mchbar_read8(0x1c8) & 0xf; - if (s->spd_type == DDR2) - i = (i + 10) % 14; - else /* DDR3 */ - i = (i + 3) % 12; - sync_dll_load_tap(i); - } + if (s->spd_type == DDR3 && s->selected_timings.mem_clk == MEM_CLOCK_1066MHz) + sync_dll_load_tap((tap + 3) % 12); + + if (s->spd_type == DDR2 && + s->selected_timings.fsb_clk == FSB_CLOCK_800MHz && + s->selected_timings.mem_clk == MEM_CLOCK_667MHz) + sync_dll_load_tap((tap + 10) % 14); switch (s->selected_timings.mem_clk) { case MEM_CLOCK_667MHz: -- cgit v1.2.3