Date: Fri, 24 Dec 2010 14:42:46 +0100 From: Clemens Ladisch Subject: 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 Signed-off-by: Stefan Richter --- drivers/firewire/ohci.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) Index: b/drivers/firewire/ohci.c =================================================================== --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -125,6 +125,7 @@ struct context { struct fw_ohci *ohci; u32 regs; int total_allocation; + bool running; bool flushing; /* @@ -1174,6 +1175,7 @@ static void context_run(struct context * 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 @@ static void context_stop(struct context 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 @@ static int at_context_queue_packet(struc 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 @@ static int at_context_queue_packet(struc 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;