firewire: ohci: cache the context run bit
The DMA context run control bit is entirely controlled by software, so
it is safe to cache it. This allows the driver to avoid doing an
additional MMIO read when queueing an AT packet.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index cfe5afe..3ae84e2 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -125,6 +125,7 @@
struct fw_ohci *ohci;
u32 regs;
int total_allocation;
+ bool running;
bool flushing;
/*
@@ -1174,6 +1175,7 @@
le32_to_cpu(ctx->last->branch_address));
reg_write(ohci, CONTROL_CLEAR(ctx->regs), ~0);
reg_write(ohci, CONTROL_SET(ctx->regs), CONTEXT_RUN | extra);
+ ctx->running = true;
flush_writes(ohci);
}
@@ -1202,6 +1204,7 @@
ctx->active = false;
reg_write(ctx->ohci, CONTROL_CLEAR(ctx->regs), CONTEXT_RUN);
+ ctx->running = false;
flush_writes(ctx->ohci);
for (i = 0; i < 10; i++) {
@@ -1232,7 +1235,6 @@
struct descriptor *d, *last;
__le32 *header;
int z, tcode;
- u32 reg;
d = context_get_descriptors(ctx, 4, &d_bus);
if (d == NULL) {
@@ -1351,9 +1353,7 @@
context_append(ctx, d, z, 4 - z);
- /* If the context isn't already running, start it up. */
- reg = reg_read(ctx->ohci, CONTROL_SET(ctx->regs));
- if ((reg & CONTEXT_RUN) == 0)
+ if (!ctx->running)
context_run(ctx, 0);
return 0;