[PATCH 01/26] x86: fsp: Reinit the FPU after FSP meminit

Simon Glass
2020-05-19T23:10:33Z

The APL FSP appears to leave the FPU in a bad state in that it has
registers in use. This causes an error when the next FPU operation is
performed.

Work around this by re-resetting the FPU after calling FSP-M. This allows
the freetype console to work correctly.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

arch/x86/cpu/i386/cpu.c | 5 +++++
arch/x86/include/asm/u-boot-x86.h | 8 ++++++++
arch/x86/lib/fsp2/fsp_meminit.c | 1 +
3 files changed, 14 insertions(+)

diff --git a/arch/x86/cpu/i386/cpu.c b/arch/x86/cpu/i386/cpu.c
index 435e50edad..d27324cb4e 100644
--- a/arch/x86/cpu/i386/cpu.c
+++ b/arch/x86/cpu/i386/cpu.c
@@ -363,6 +363,11 @@ static void setup_cpu_features(void)
: : "i" (em_rst), "i" (mp_ne_set) : "eax");
}

+void cpu_reinit_fpu(void)
+{
+ asm ("fninit\n");
+}
+
static void setup_identity(void)
{
/* identify CPU via cpuid and store the decoded info into gd->arch */
diff --git a/arch/x86/include/asm/u-boot-x86.h b/arch/x86/include/asm/u-boot-x86.h
index 3e5d56d075..bd3f44014c 100644
--- a/arch/x86/include/asm/u-boot-x86.h
+++ b/arch/x86/include/asm/u-boot-x86.h
@@ -43,6 +43,14 @@ int x86_cpu_reinit_f(void);
*/
int x86_cpu_init_tpl(void);

+/**
+ * cpu_reinit_fpu() - Reinit the FPU if something is wrong with it
+ *
+ * The FSP-M code can leave registers in use in the FPU. This functions reinits
+ * it so that the FPU can be used safely
+ */
+void cpu_reinit_fpu(void);
+
int cpu_init_f(void);
void setup_gdt(struct global_data *id, u64 *gdt_addr);
/*
diff --git a/arch/x86/lib/fsp2/fsp_meminit.c b/arch/x86/lib/fsp2/fsp_meminit.c
index 1a758147b0..faf9c29aef 100644
--- a/arch/x86/lib/fsp2/fsp_meminit.c
+++ b/arch/x86/lib/fsp2/fsp_meminit.c
@@ -85,6 +85,7 @@ int fsp_memory_init(bool s3wake, bool use_spi_flash)
func = (fsp_memory_init_func)(hdr->img_base + hdr->fsp_mem_init);
ret = func(&upd, &hob);
bootstage_accum(BOOTSTAGE_ID_ACCUM_FSP_M);
+ cpu_reinit_fpu();
if (ret)
return log_msg_ret("SDRAM init fail\n", ret);

--
2.26.2.761.g0e0b3e54be-goog