From 386a4153a2c1455e424f280d636efa3c91864466 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Fri, 24 Dec 2010 14:42:46 +0100 Subject: [PATCH] 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(-) diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index cfe5afe359c6..3ae84e2c5192 100644 --- 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 *ctx, u32 extra) 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) 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(struct context *ctx, 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(struct context *ctx, 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;