From patchwork Wed Nov 12 12:11:43 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: NIU driver: Sun x8 Express Quad Gigabit Ethernet Adapter From: David Miller X-Patchwork-Id: 8355 X-Patchwork-Delegate: davem@davemloft.net Message-Id: <20081112.041143.11487260.davem@davemloft.net> To: jdb@comx.dk Cc: netdev@vger.kernel.org Date: Wed, 12 Nov 2008 04:11:43 -0800 (PST) From: David Miller Date: Wed, 12 Nov 2008 03:52:40 -0800 (PST) > Ok, Jesper, please try two things for me, leave the debugging patch > in there for all the tests: > > 1) Retrigger the problem (with or without MSI, doesn't matter) but > add back in that test I asked you to try last week. The one > where the "if (++rp->mark_counter == rp->mark_freq)" condition > test in niu_start_xmit() is commented out, so that the > "mrk |= TX_DESC_MARK;" statement always runs. > > Get me the log dump produced by that scenerio. > > 2) Next, simply comment out the: > > if (unlikely(!(cs & (TX_CS_MK | TX_CS_MMK)))) > goto out; > > lines in niu_tx_work(). > > Let's see what new info we can get out of this. These tests are still useful for me, so please perform them, but I think I've found the bug. I am guessing you're running a 32-bit x86 kernel. In such a case the driver has to define a local readq() and writeq() implementation. What I provide for NIU right now reads the upper 32-bits then the lower 32-bits of the register. Guess what that does? The packet counters live in the upper 32-bits and the MARK bits live in the lower 32-bits of the TX_CS register. So it first reads the packet counters, and as a side effect that clears the MARK bits in the TX_CS register. So when we read the lower 32-bits the MARK bits are always seen as zero. BzzaaarT! So the following patch should fix this bug. writeq() should be OK as-is, so doesn't need a similar change. Tested-by: Jesper Dangaard Brouer --- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/net/niu.c b/drivers/net/niu.c index 9acb5d7..d8463b1 100644 --- a/drivers/net/niu.c +++ b/drivers/net/niu.c @@ -51,8 +51,7 @@ MODULE_VERSION(DRV_MODULE_VERSION); #ifndef readq static u64 readq(void __iomem *reg) { - return (((u64)readl(reg + 0x4UL) << 32) | - (u64)readl(reg)); + return ((u64) readl(reg)) | (((u64) readl(reg + 4UL)) << 32); } static void writeq(u64 val, void __iomem *reg)