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powerpc/64: Set DSCR default initially from SPR

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Take the DSCR value set by firmware as the dscr_default value,
rather than zero.

POWER9 recommends DSCR default to a non-zero value.

Signed-off-by: From: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make record_spr_defaults() __init]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-10-24 21:44:44 +10:00 committed by Michael Ellerman
parent 339a3293f4
commit 1696d0fb7f
3 changed files with 26 additions and 0 deletions
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6
arch/powerpc/kernel/setup.h
View File

@ -45,6 +45,12 @@ void emergency_stack_init(void);
static inline void emergency_stack_init(void) { };
#endif
#ifdef CONFIG_PPC64
void record_spr_defaults(void);
#else
static inline void record_spr_defaults(void) { };
#endif
/*
* Having this in kvm_ppc.h makes include dependencies too
* tricky to solve for setup-common.c so have it here.

9
arch/powerpc/kernel/setup_64.c
View File

@ -69,6 +69,8 @@
#include <asm/opal.h>
#include <asm/cputhreads.h>
#include "setup.h"
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
@ -316,6 +318,13 @@ void __init early_setup(unsigned long dt_ptr)
/* Initialize the hash table or TLB handling */
early_init_mmu();
/*
* After firmware and early platform setup code has set things up,
* we note the SPR values for configurable control/performance
* registers, and use those as initial defaults.
*/
record_spr_defaults();
/*
* At this point, we can let interrupts switch to virtual mode
* (the MMU has been setup), so adjust the MSR in the PACA to

11
arch/powerpc/kernel/sysfs.c
View File

@ -590,6 +590,17 @@ static void sysfs_create_dscr_default(void)
if (cpu_has_feature(CPU_FTR_DSCR))
err = device_create_file(cpu_subsys.dev_root, &dev_attr_dscr_default);
}
void __init record_spr_defaults(void)
{
int cpu;
if (cpu_has_feature(CPU_FTR_DSCR)) {
dscr_default = mfspr(SPRN_DSCR);
for (cpu = 0; cpu < nr_cpu_ids; cpu++)
paca[cpu].dscr_default = dscr_default;
}
}
#endif /* CONFIG_PPC64 */
#ifdef HAS_PPC_PMC_PA6T