This is a note to let you know that I've just added the patch titled
r8152: limit the RX buffer size of RTL8153A for USB 2.0
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
r8152-limit-the-rx-buffer-size-of-rtl8153a-for-usb-2.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0ad9b1d46517aad4d2433b578ab0977cb1a77466
Author: Hayes Wang <hayeswang@xxxxxxxxxxx>
Date: Fri Mar 19 15:37:21 2021 +0800
r8152: limit the RX buffer size of RTL8153A for USB 2.0
[ Upstream commit f91a50d8b51b5c8ef1cfb08115a005bba4250507 ]
If the USB host controller is EHCI, the throughput is reduced from
300Mb/s to 60Mb/s, when the rx buffer size is modified from 16K to
32K.
According to the EHCI spec, the maximum size of the qTD is 20K.
Therefore, when the driver uses more than 20K buffer, the latency
time of EHCI would be increased. And, it let the RTL8153A get worse
throughput.
However, the driver uses alloc_pages() for rx buffer, so I limit
the rx buffer to 16K rather than 20K.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=205923
Fixes: ec5791c202ac ("r8152: separate the rx buffer size")
Reported-by: Robert Davies <robdavies1977@xxxxxxxxx>
Signed-off-by: Hayes Wang <hayeswang@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index d2862071b697..f5010f8ac1ec 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -6519,7 +6519,10 @@ static int rtl_ops_init(struct r8152 *tp)
ops->in_nway = rtl8153_in_nway;
ops->hw_phy_cfg = r8153_hw_phy_cfg;
ops->autosuspend_en = rtl8153_runtime_enable;
- tp->rx_buf_sz = 32 * 1024;
+ if (tp->udev->speed < USB_SPEED_SUPER)
+ tp->rx_buf_sz = 16 * 1024;
+ else
+ tp->rx_buf_sz = 32 * 1024;
tp->eee_en = true;
tp->eee_adv = MDIO_EEE_1000T | MDIO_EEE_100TX;
break;
