Date: Mon, 16 May 2011 08:10:10 +0200 From: Clemens Ladisch Subject: firewire: ohci: remove superfluous posted write flushes The call to flush_writes() in context_stop() is superfluous because another register read is done immediately afterwards. The call to flush_writes() in ar_context_run() does not need to be done individually for each AR context, so move it to ohci_enable(). This also makes ohci_enable() clearer because it no longer depends on a side effect of ar_context_run() to flush its own register writes. Finally, the setting of a context's wake bit does not need to be flushed because neither the driver logic nor the API require the CPU to wait for this action. This removes the last MMIO reads from the packet queueing code paths. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter --- drivers/firewire/ohci.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) Index: b/drivers/firewire/ohci.c =================================================================== --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -629,7 +629,6 @@ static void ar_context_link_page(struct ctx->last_buffer_index = index; reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); - flush_writes(ctx->ohci); } static void ar_context_release(struct ar_context *ctx) @@ -1001,7 +1000,6 @@ static void ar_context_run(struct ar_con reg_write(ctx->ohci, COMMAND_PTR(ctx->regs), ctx->descriptors_bus | 1); reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_RUN); - flush_writes(ctx->ohci); } static struct descriptor *find_branch_descriptor(struct descriptor *d, int z) @@ -1201,7 +1199,6 @@ static void context_stop(struct context reg_write(ctx->ohci, CONTROL_CLEAR(ctx->regs), CONTEXT_RUN); ctx->running = false; - flush_writes(ctx->ohci); for (i = 0; i < 10; i++) { reg = reg_read(ctx->ohci, CONTROL_SET(ctx->regs)); @@ -1345,12 +1342,10 @@ static int at_context_queue_packet(struc context_append(ctx, d, z, 4 - z); - if (ctx->running) { + if (ctx->running) reg_write(ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); - flush_writes(ohci); - } else { + else context_run(ctx, 0); - } return 0; } @@ -2196,7 +2191,9 @@ static int ohci_enable(struct fw_card *c OHCI1394_LinkControl_rcvPhyPkt); ar_context_run(&ohci->ar_request_ctx); - ar_context_run(&ohci->ar_response_ctx); /* also flushes writes */ + ar_context_run(&ohci->ar_response_ctx); + + flush_writes(ohci); /* We are ready to go, reset bus to finish initialization. */ fw_schedule_bus_reset(&ohci->card, false, true); @@ -3128,7 +3125,6 @@ static void ohci_flush_queue_iso(struct &container_of(base, struct iso_context, base)->context; reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); - flush_writes(ctx->ohci); } static const struct fw_card_driver ohci_driver = {