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authorGrant Likely <grant.likely@secretlab.ca>2008-12-21 02:54:28 -0700
committerGrant Likely <grant.likely@secretlab.ca>2008-12-21 02:54:28 -0700
commitaaab5e83c2c25d94f7409bdc947a5cc383514e15 (patch)
tree929571b5bf2728ac8494b56d0c4965b2aaa47da8
parente4efe3c271c5498ffe7e167eaff01514be2b9a77 (diff)
powerpc/mpc5200: Disable bestcomm prefetching when ATA DMA enabled
When ATA DMA is enabled, bestcomm prefetching does not work. This patch adds a function to disable bestcomm prefetch when the ATA Bestcomm task is initialized. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
-rw-r--r--arch/powerpc/sysdev/bestcomm/ata.c3
-rw-r--r--arch/powerpc/sysdev/bestcomm/bestcomm.c7
-rw-r--r--arch/powerpc/sysdev/bestcomm/bestcomm_priv.h16
3 files changed, 21 insertions, 5 deletions
diff --git a/arch/powerpc/sysdev/bestcomm/ata.c b/arch/powerpc/sysdev/bestcomm/ata.c
index 1f5258fb38c..901c9f91e5d 100644
--- a/arch/powerpc/sysdev/bestcomm/ata.c
+++ b/arch/powerpc/sysdev/bestcomm/ata.c
@@ -61,6 +61,9 @@ bcom_ata_init(int queue_len, int maxbufsize)
struct bcom_ata_var *var;
struct bcom_ata_inc *inc;
+ /* Prefetch breaks ATA DMA. Turn it off for ATA DMA */
+ bcom_disable_prefetch();
+
tsk = bcom_task_alloc(queue_len, sizeof(struct bcom_ata_bd), 0);
if (!tsk)
return NULL;
diff --git a/arch/powerpc/sysdev/bestcomm/bestcomm.c b/arch/powerpc/sysdev/bestcomm/bestcomm.c
index 446c9ea85b3..378ebd9aac1 100644
--- a/arch/powerpc/sysdev/bestcomm/bestcomm.c
+++ b/arch/powerpc/sysdev/bestcomm/bestcomm.c
@@ -279,7 +279,6 @@ bcom_engine_init(void)
int task;
phys_addr_t tdt_pa, ctx_pa, var_pa, fdt_pa;
unsigned int tdt_size, ctx_size, var_size, fdt_size;
- u16 regval;
/* Allocate & clear SRAM zones for FDT, TDTs, contexts and vars/incs */
tdt_size = BCOM_MAX_TASKS * sizeof(struct bcom_tdt);
@@ -331,10 +330,8 @@ bcom_engine_init(void)
out_8(&bcom_eng->regs->ipr[BCOM_INITIATOR_ALWAYS], BCOM_IPR_ALWAYS);
/* Disable COMM Bus Prefetch on the original 5200; it's broken */
- if ((mfspr(SPRN_SVR) & MPC5200_SVR_MASK) == MPC5200_SVR) {
- regval = in_be16(&bcom_eng->regs->PtdCntrl);
- out_be16(&bcom_eng->regs->PtdCntrl, regval | 1);
- }
+ if ((mfspr(SPRN_SVR) & MPC5200_SVR_MASK) == MPC5200_SVR)
+ bcom_disable_prefetch();
/* Init lock */
spin_lock_init(&bcom_eng->lock);
diff --git a/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h b/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
index 746f1551c8a..eb0d1c883c3 100644
--- a/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
+++ b/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
@@ -241,6 +241,22 @@ extern void bcom_set_initiator(int task, int initiator);
#define TASK_ENABLE 0x8000
+/**
+ * bcom_disable_prefetch - Hook to disable bus prefetching
+ *
+ * ATA DMA and the original MPC5200 need this due to silicon bugs. At the
+ * moment disabling prefetch is a one-way street. There is no mechanism
+ * in place to turn prefetch back on after it has been disabled. There is
+ * no reason it couldn't be done, it would just be more complex to implement.
+ */
+static inline void bcom_disable_prefetch(void)
+{
+ u16 regval;
+
+ regval = in_be16(&bcom_eng->regs->PtdCntrl);
+ out_be16(&bcom_eng->regs->PtdCntrl, regval | 1);
+};
+
static inline void
bcom_enable_task(int task)
{