There are several outstanding issues as to why this does not apply to FSP1:
* For FSP1, the system memory and reserved memory used by FSP are already programmed in the MTRR by FSP. * The 'mtrr_top' mistakenly includes TSEG memory range that has the same RES_MEM_RESERVED resource type. Its address is programmed and reported by FSP to be near the top of 4 GiB space, which is not what we want for SDRAM. * The call to mtrr_add_request() is not guaranteed to have its size to be exactly the power of 2. This causes reserved bits of the IA32_MTRR_PHYSMASK register to be written which generates #GP.
For FSP2, it seems this is necessary as without this, U-Boot boot process on Chromebook Coral goes very slowly.
Signed-off-by: Bin Meng bmeng.cn@gmail.com
---
Changes in v2: - Keep programing MTRR to FSP2 only
arch/x86/lib/fsp/fsp_dram.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/arch/x86/lib/fsp/fsp_dram.c b/arch/x86/lib/fsp/fsp_dram.c index 8ad9aeedac..2bd408d0c5 100644 --- a/arch/x86/lib/fsp/fsp_dram.c +++ b/arch/x86/lib/fsp/fsp_dram.c @@ -48,12 +48,28 @@ int dram_init_banksize(void) phys_addr_t mtrr_top; phys_addr_t low_end; uint bank; + bool update_mtrr; + + /* + * For FSP1, the system memory and reserved memory used by FSP are + * already programmed in the MTRR by FSP. Also it is observed that + * FSP on Intel Queensbay platform reports the TSEG memory range + * that has the same RES_MEM_RESERVED resource type whose address + * is programmed by FSP to be near the top of 4 GiB space, which is + * not what we want for DRAM. + * + * However it seems FSP2's behavior is different. We need to add the + * DRAM range in MTRR otherwise the boot process goes very slowly, + * which was observed on Chrromebook Coral with FSP2. + */ + update_mtrr = CONFIG_IS_ENABLED(FSP_VERSION2);
if (!ll_boot_init()) { gd->bd->bi_dram[0].start = 0; gd->bd->bi_dram[0].size = gd->ram_size;
- mtrr_add_request(MTRR_TYPE_WRBACK, 0, gd->ram_size); + if (update_mtrr) + mtrr_add_request(MTRR_TYPE_WRBACK, 0, gd->ram_size); return 0; }
@@ -76,8 +92,10 @@ int dram_init_banksize(void) } else { gd->bd->bi_dram[bank].start = res_desc->phys_start; gd->bd->bi_dram[bank].size = res_desc->len; - mtrr_add_request(MTRR_TYPE_WRBACK, res_desc->phys_start, - res_desc->len); + if (update_mtrr) + mtrr_add_request(MTRR_TYPE_WRBACK, + res_desc->phys_start, + res_desc->len); log_debug("ram %llx %llx\n", gd->bd->bi_dram[bank].start, gd->bd->bi_dram[bank].size); @@ -92,7 +110,8 @@ int dram_init_banksize(void) * Set up an MTRR to the top of low, reserved memory. This is necessary * for graphics to run at full speed in U-Boot. */ - mtrr_add_request(MTRR_TYPE_WRBACK, 0, mtrr_top); + if (update_mtrr) + mtrr_add_request(MTRR_TYPE_WRBACK, 0, mtrr_top);
return 0; }