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pflash: Restore & fix lazy ROMD switching 

Commit 5145b3d1cc revealed a bug in the lazy ROMD switch-back logic, but
resolved it by breaking that feature. This approach addresses the issue
by switching back to ROMD after a certain amount of read accesses
without further unlock sequences.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Jan Kiszka 2011-04-10 12:53:39 +02:00 committed by Aurelien Jarno
parent 70afb8ff90
commit 661bfc80e8
1 changed files with 8 additions and 4 deletions
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12
hw/pflash_cfi02.c
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@ -50,6 +50,8 @@ do { \
#define DPRINTF(fmt, ...) do { } while (0)
#endif
#define PFLASH_LAZY_ROMD_THRESHOLD 42
struct pflash_t {
BlockDriverState *bs;
target_phys_addr_t base;
@ -70,6 +72,7 @@ struct pflash_t {
ram_addr_t off;
int fl_mem;
int rom_mode;
int read_counter; /* used for lazy switch-back to rom mode */
void *storage;
};
@ -112,10 +115,10 @@ static uint32_t pflash_read (pflash_t *pfl, target_phys_addr_t offset,
DPRINTF("%s: offset " TARGET_FMT_plx "\n", __func__, offset);
ret = -1;
if (!pfl->rom_mode) {
/* Lazy reset of to ROMD mode */
if (pfl->wcycle == 0)
pflash_register_memory(pfl, 1);
/* Lazy reset to ROMD mode after a certain amount of read accesses */
if (!pfl->rom_mode && pfl->wcycle == 0 &&
++pfl->read_counter > PFLASH_LAZY_ROMD_THRESHOLD) {
pflash_register_memory(pfl, 1);
}
offset &= pfl->chip_len - 1;
boff = offset & 0xFF;
@ -254,6 +257,7 @@ static void pflash_write (pflash_t *pfl, target_phys_addr_t offset,
/* Set the device in I/O access mode if required */
if (pfl->rom_mode)
pflash_register_memory(pfl, 0);
pfl->read_counter = 0;
/* We're in read mode */
check_unlock0:
if (boff == 0x55 && cmd == 0x98) {