netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Harini Katakam <harini.katakam@xilinx.com>
To: nicolas.ferre@microchip.com, davem@davemloft.net,
	claudiu.beznea@microchip.com, kuba@kernel.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	michal.simek@xilinx.com, harinikatakamlinux@gmail.com,
	harini.katakam@xilinx.com
Subject: [PATCH v2 2/2] net: macb: Limit maximum GEM TX length in TSO
Date: Mon,  3 Feb 2020 18:48:02 +0530	[thread overview]
Message-ID: <1580735882-7429-3-git-send-email-harini.katakam@xilinx.com> (raw)
In-Reply-To: <1580735882-7429-1-git-send-email-harini.katakam@xilinx.com>

GEM_MAX_TX_LEN currently resolves to 0x3FF8 for any IP version supporting
TSO with full 14bits of length field in payload descriptor. But an IP
errata causes false amba_error (bit 6 of ISR) when length in payload
descriptors is specified above 16387. The error occurs because the DMA
falsely concludes that there is not enough space in SRAM for incoming
payload. These errors were observed continuously under stress of large
packets using iperf on a version where SRAM was 16K for each queue. This
errata will be documented shortly and affects all versions since TSO
functionality was added. Hence limit the max length to 0x3FC0 (rounded).

Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
---
v2:
Use 0x3FC0 by default

 drivers/net/ethernet/cadence/macb_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 2e418b8..cca321c 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -73,7 +73,7 @@ struct sifive_fu540_macb_mgmt {
 /* Max length of transmit frame must be a multiple of 8 bytes */
 #define MACB_TX_LEN_ALIGN	8
 #define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
-#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		(unsigned int)(0x3FC0)
 
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
 #define MACB_NETIF_LSO		NETIF_F_TSO
-- 
2.7.4


  parent reply	other threads:[~2020-02-03 13:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-03 13:18 [PATCH v2 0/2] TSO bug fixes Harini Katakam
2020-02-03 13:18 ` [PATCH v2 1/2] net: macb: Remove unnecessary alignment check for TSO Harini Katakam
2020-02-04  9:37   ` David Miller
     [not found]     ` <BN7PR02MB5121912B4AE8633C50D6DE98C9030@BN7PR02MB5121.namprd02.prod.outlook.com>
2020-02-04 10:22       ` Harini Katakam
2020-02-04 11:43         ` David Miller
2020-02-03 13:18 ` Harini Katakam [this message]
2020-02-04  9:37   ` [PATCH v2 2/2] net: macb: Limit maximum GEM TX length in TSO David Miller
     [not found]     ` <BN7PR02MB51215810D1240E98E81F6176C9030@BN7PR02MB5121.namprd02.prod.outlook.com>
2020-02-04 10:26       ` Harini Katakam

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1580735882-7429-3-git-send-email-harini.katakam@xilinx.com \
    --to=harini.katakam@xilinx.com \
    --cc=claudiu.beznea@microchip.com \
    --cc=davem@davemloft.net \
    --cc=harinikatakamlinux@gmail.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michal.simek@xilinx.com \
    --cc=netdev@vger.kernel.org \
    --cc=nicolas.ferre@microchip.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).