[v6,03/22] usb: dwc2: host: Set host_rx_fifo_size to 525 for rk3066
diff mbox

Message ID 1454034013-24657-4-git-send-email-dianders@chromium.org
State New
Headers show

Commit Message

Doug Anderson Jan. 29, 2016, 2:19 a.m. UTC
As documented in dwc2_calculate_dynamic_fifo(), host_rx_fifo_size should
really be:
 2 * ((Largest Packet size / 4) + 1 + 1) + n
 with n = number of host channel.

We have 9 host channels, so
 2 * ((1024/4) + 2) + 9 = 516 + 9 = 525

We've got 960 / 972 total_fifo_size on rk3288 (and presumably on
rk3066) and 525 + 128 + 256 = 909 so we're still under on both ports
even when we increment by 5.

In the future, it would be nice if dwc2_calculate_dynamic_fifo() could
handle the "too small" FIFO case and come up with something more
dynamically.  When we do that we can figure out how to allocate the
extra 48 / 60 bytes of FIFO that we're currently wasting.

NOTE: no known bugs are fixed by this patch, but it seems like a simple
fix and ought to fix someone.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
---
Changes in v6:
- Back to 525 dwords, not 528.
- Add Kever's Reviewed-by.
- Add Heiko's Tested-by.

Changes in v5: None
Changes in v4:
- Set host_rx_fifo_size to 528 for rk3066 new for v4.

Changes in v3: None
Changes in v2: None

 drivers/usb/dwc2/platform.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch
diff mbox

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 5008a467ce06..b277e521a311 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -126,7 +126,7 @@  static const struct dwc2_core_params params_rk3066 = {
 	.speed				= -1,
 	.enable_dynamic_fifo		= 1,
 	.en_multiple_tx_fifo		= -1,
-	.host_rx_fifo_size		= 520,	/* 520 DWORDs */
+	.host_rx_fifo_size		= 525,	/* 525 DWORDs */
 	.host_nperio_tx_fifo_size	= 128,	/* 128 DWORDs */
 	.host_perio_tx_fifo_size	= 256,	/* 256 DWORDs */
 	.max_transfer_size		= -1,