Unverified Commit fa7d7339 authored by Samuel Holland's avatar Samuel Holland Committed by Palmer Dabbelt
Browse files

riscv: Do not save the scratch CSR during suspend 



While the processor is executing kernel code, the value of the scratch
CSR is always zero, so there is no need to save the value. Continue to
write the CSR during the resume flow, so we do not rely on firmware to
initialize it.

Signed-off-by: default avatarSamuel Holland <samuel.holland@sifive.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240312195641.1830521-1-samuel.holland@sifive.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent d4b500cc

arch/riscv/include/asm/suspend.h

+0 −1
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ struct suspend_context { 
	/* Saved and restored by low-level functions */

	struct pt_regs regs;

	/* Saved and restored by high-level functions */

	unsigned long scratch;

	unsigned long envcfg;

	unsigned long tvec;

	unsigned long ie;

arch/riscv/kernel/suspend.c

+1 −2
Original line number Diff line number Diff line
@@ -14,7 +14,6 @@ 


void suspend_save_csrs(struct suspend_context *context)

{

	context->scratch = csr_read(CSR_SCRATCH);

	if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG))

		context->envcfg = csr_read(CSR_ENVCFG);

	context->tvec = csr_read(CSR_TVEC);
@@ -37,7 +36,7 @@ void suspend_save_csrs(struct suspend_context *context) 


void suspend_restore_csrs(struct suspend_context *context)

{

	csr_write(CSR_SCRATCH, context->scratch);

	csr_write(CSR_SCRATCH, 0);

	if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG))

		csr_write(CSR_ENVCFG, context->envcfg);

	csr_write(CSR_TVEC, context->tvec);