From 528314b503f855b268ae7861ea4e206fbbfb8356 Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Fri, 22 Feb 2019 10:00:10 -0700 Subject: dmaengine: ioatdma: support latency tolerance report (LTR) for v3.4 IOATDMA 3.4 supports PCIe LTR mechanism. The registers are non-standard PCIe LTR support. This needs to be setup in order to not suffer performance impact and provide proper power management. The channel is set to active when it is allocated, and to passive when it's freed. Signed-off-by: Dave Jiang Signed-off-by: Vinod Koul --- drivers/dma/ioat/init.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'drivers/dma/ioat/init.c') diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c index 020bcdecb3fb..d41dc9a9ff68 100644 --- a/drivers/dma/ioat/init.c +++ b/drivers/dma/ioat/init.c @@ -638,6 +638,11 @@ static void ioat_free_chan_resources(struct dma_chan *c) ioat_stop(ioat_chan); ioat_reset_hw(ioat_chan); + /* Put LTR to idle */ + if (ioat_dma->version >= IOAT_VER_3_4) + writeb(IOAT_CHAN_LTR_SWSEL_IDLE, + ioat_chan->reg_base + IOAT_CHAN_LTR_SWSEL_OFFSET); + spin_lock_bh(&ioat_chan->cleanup_lock); spin_lock_bh(&ioat_chan->prep_lock); descs = ioat_ring_space(ioat_chan); @@ -727,6 +732,28 @@ static int ioat_alloc_chan_resources(struct dma_chan *c) spin_unlock_bh(&ioat_chan->prep_lock); spin_unlock_bh(&ioat_chan->cleanup_lock); + /* Setting up LTR values for 3.4 or later */ + if (ioat_chan->ioat_dma->version >= IOAT_VER_3_4) { + u32 lat_val; + + lat_val = IOAT_CHAN_LTR_ACTIVE_SNVAL | + IOAT_CHAN_LTR_ACTIVE_SNLATSCALE | + IOAT_CHAN_LTR_ACTIVE_SNREQMNT; + writel(lat_val, ioat_chan->reg_base + + IOAT_CHAN_LTR_ACTIVE_OFFSET); + + lat_val = IOAT_CHAN_LTR_IDLE_SNVAL | + IOAT_CHAN_LTR_IDLE_SNLATSCALE | + IOAT_CHAN_LTR_IDLE_SNREQMNT; + writel(lat_val, ioat_chan->reg_base + + IOAT_CHAN_LTR_IDLE_OFFSET); + + /* Select to active */ + writeb(IOAT_CHAN_LTR_SWSEL_ACTIVE, + ioat_chan->reg_base + + IOAT_CHAN_LTR_SWSEL_OFFSET); + } + ioat_start_null_desc(ioat_chan); /* check that we got off the ground */ -- cgit v1.2.3-58-ga151