[PATCH 4.9 32/62] thunderbolt: Use 32-bit writes when writing ring producer/consumer

Greg Kroah-Hartman
2019-11-04T22:27:16Z

From: Mika Westerberg <mika.westerberg@linux.intel.com>

[ Upstream commit 943795219d3cb9f8ce6ce51cad3ffe1f61e95c6b ]

The register access should be using 32-bit reads/writes according to the
datasheet. With the previous generation hardware 16-bit writes have been
working but starting with ICL this is not the case anymore so fix
producer/consumer register update to use correct width register address.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <YehezkelShB@gmail.com>
Tested-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/thunderbolt/nhi.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index cba6bc6ab9ed7..c963593eedbe7 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -95,9 +95,20 @@ static void __iomem *ring_options_base(struct tb_ring *ring)
return io;
}

-static void ring_iowrite16desc(struct tb_ring *ring, u32 value, u32 offset)
+static void ring_iowrite_cons(struct tb_ring *ring, u16 cons)
{
- iowrite16(value, ring_desc_base(ring) + offset);
+ /*
+ * The other 16-bits in the register is read-only and writes to it
+ * are ignored by the hardware so we can save one ioread32() by
+ * filling the read-only bits with zeroes.
+ */
+ iowrite32(cons, ring_desc_base(ring) + 8);
+}
+
+static void ring_iowrite_prod(struct tb_ring *ring, u16 prod)
+{
+ /* See ring_iowrite_cons() above for explanation */
+ iowrite32(prod << 16, ring_desc_base(ring) + 8);
}

static void ring_iowrite32desc(struct tb_ring *ring, u32 value, u32 offset)
@@ -149,7 +160,10 @@ static void ring_write_descriptors(struct tb_ring *ring)
descriptor->sof = frame->sof;
}
ring->head = (ring->head + 1) % ring->size;
- ring_iowrite16desc(ring, ring->head, ring->is_tx ? 10 : 8);
+ if (ring->is_tx)
+ ring_iowrite_prod(ring, ring->head);
+ else
+ ring_iowrite_cons(ring, ring->head);
}
}

@@ -369,7 +383,7 @@ void ring_stop(struct tb_ring *ring)

ring_iowrite32options(ring, 0, 0);
ring_iowrite64desc(ring, 0, 0);
- ring_iowrite16desc(ring, 0, ring->is_tx ? 10 : 8);
+ ring_iowrite32desc(ring, 0, 8);
ring_iowrite32desc(ring, 0, 12);
ring->head = 0;
ring->tail = 0;
--
2.20.1