From: YeeLi <seven.yi.lee@gmail.com>
To: jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
davem@davemloft.net, kuba@kernel.org
Cc: intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org,
seven.yi.lee@gmail.com
Subject: [PATCH] driver core: fix e1000e ltr bug
Date: Tue, 29 Jun 2021 16:21:28 +0800 [thread overview]
Message-ID: <20210629082128.255988-1-seven.yi.lee@gmail.com> (raw)
In e1000e driver, a PCIe-like device, the max snoop/no-snoop latency
is the upper limit.So, directly compare the size of lat_enc and
max_ltr_enc is incorrect.
In 1000Mbps, 0x8b9 < 0x1003, 189440 ns < 3145728 ns, correct.
In 100Mbps, 0xc3a < 0x1003, 1900544 ns < 3145728 ns, correct.
In 10Mbps, 0xe40 < 0x1003, 18874368 > 3145728, incorrect.
Decoded the lat_enc and max_ltr_enc before compare them is necessary.
Signed-off-by: YeeLi <seven.yi.lee@gmail.com>
---
drivers/net/ethernet/intel/e1000e/ich8lan.c | 23 ++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index 590ad110d383..3bff1b570b76 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -986,6 +986,27 @@ static s32 e1000_k1_workaround_lpt_lp(struct e1000_hw *hw, bool link)
return ret_val;
}
+static u32 convert_e1000e_ltr_scale(u32 val)
+{
+ if (val > 5)
+ return 0;
+
+ return 1U << (5 * val);
+}
+
+static u64 decoded_ltr(u32 val)
+{
+ u64 decoded_latency;
+ u32 value;
+ u32 scale;
+
+ value = val & 0x03FF;
+ scale = (val & 0x1C00) >> 10;
+ decoded_latency = value * convert_e1000e_ltr_scale(scale);
+
+ return decoded_latency;
+}
+
/**
* e1000_platform_pm_pch_lpt - Set platform power management values
* @hw: pointer to the HW structure
@@ -1059,7 +1080,7 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
E1000_PCI_LTR_CAP_LPT + 2, &max_nosnoop);
max_ltr_enc = max_t(u16, max_snoop, max_nosnoop);
- if (lat_enc > max_ltr_enc)
+ if (decoded_ltr(lat_enc) > decoded_ltr(max_ltr_enc))
lat_enc = max_ltr_enc;
}
--
2.25.1
next reply other threads:[~2021-06-29 8:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-29 8:21 YeeLi [this message]
2021-06-29 14:49 ` [Intel-wired-lan] [PATCH] driver core: fix e1000e ltr bug Neftin, Sasha
[not found] ` <CALX8JfQymbSmCP0xk0C-=v64__uaH=BR0UZjr2yRyLWVwm9dLQ@mail.gmail.com>
2021-06-30 6:13 ` Neftin, Sasha
[not found] ` <CALX8JfTOG7bXn7gP+4n1_3CfFFk6aL-RJDY03RCOeBSpUeTEPQ@mail.gmail.com>
2021-07-01 8:34 ` Neftin, Sasha
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