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From:   Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
To:     linux-kernel@vger.kernel.org
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        nic_swsd@realtek.com,
        Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>,
        Marco Elver <elver@google.com>,
        Jacob Keller <jacob.e.keller@intel.com>
Subject: [PATCH net-next v6 2/5] r8169: Coalesce RTL8411b PHY power-down recovery calls to reduce spinlock stalls
Date:   Sat,  4 Nov 2023 23:15:15 +0100
Message-Id: <20231104221514.45821-3-mirsad.todorovac@alu.unizg.hr>
In-Reply-To: <20231104221514.45821-1-mirsad.todorovac@alu.unizg.hr>
References: <20231104221514.45821-1-mirsad.todorovac@alu.unizg.hr>
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On RTL8411b the RX unit gets confused if the PHY is powered-down.
This was reported in [0] and confirmed by Realtek. Realtek provided
a sequence to fix the RX unit after PHY wakeup.

A series of about 130 r8168_mac_ocp_write() calls is performed to
program the RTL registers for recovery.

With about 130 of these sequential calls to r8168_mac_ocp_write() this looks like
a lock storm that will stall all of the cores sharing the same cache for certain
time I/O takes to finish.

In a sequential case of RTL register programming, a sequence of writes to the RTL
registers can be coalesced under a same raw spinlock. This can dramatically decrease
the number of bus stalls in a multicore or multi-CPU system.

Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: nic_swsd@realtek.com
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/lkml/20231028005153.2180411-1-mirsad.todorovac@alu.unizg.hr/
Link: https://lore.kernel.org/lkml/20231028110459.2644926-1-mirsad.todorovac@alu.unizg.hr/
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
---
v6:
 proceeded according to Jacob Keller's suggestions by creating a cover page and reducing
 the text within the commits. Applying to the net-next tree as Heiner Kallweit requested.

v5:
 attempted some new optimisations, which were rejected, but not all and not completely.

v4:
 fixed complaints as advised by Heiner and checkpatch.pl.
 split the patch into five sections to be more easily manipulated and reviewed
 introduced r8168_mac_ocp_write_seq()
 applied coalescing of mac ocp writes/modifies for 8168H, 8125 and 8125B

v3:
 removed register/mask pair array sentinels, so using ARRAY_SIZE().
 avoided duplication of RTL_W32() call code as advised by Heiner.

 drivers/net/ethernet/realtek/r8169_main.c | 173 ++++++----------------
 1 file changed, 46 insertions(+), 127 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index e39b5777d67b..5515c51b6e3c 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -3157,145 +3157,64 @@ static void rtl_hw_start_8411_2(struct rtl8169_private *tp)
 		{ 0x1d, 0x0000,	0x4000 },
 	};
 
-	rtl_hw_start_8168g(tp);
+	static const struct e_info_regdata init_zero_seq[] = {
+		{ 0xFC28, 0x0000 }, { 0xFC2A, 0x0000 }, { 0xFC2C, 0x0000 }, { 0xFC2E, 0x0000 },
+		{ 0xFC30, 0x0000 }, { 0xFC32, 0x0000 }, { 0xFC34, 0x0000 }, { 0xFC36, 0x0000 },
+	};
 
+	static const struct e_info_regdata recover_seq[] = {
+		{ 0xF800, 0xE008 }, { 0xF802, 0xE00A }, { 0xF804, 0xE00C }, { 0xF806, 0xE00E },
+		{ 0xF808, 0xE027 }, { 0xF80A, 0xE04F }, { 0xF80C, 0xE05E }, { 0xF80E, 0xE065 },
+		{ 0xF810, 0xC602 }, { 0xF812, 0xBE00 }, { 0xF814, 0x0000 }, { 0xF816, 0xC502 },
+		{ 0xF818, 0xBD00 }, { 0xF81A, 0x074C }, { 0xF81C, 0xC302 }, { 0xF81E, 0xBB00 },
+		{ 0xF820, 0x080A }, { 0xF822, 0x6420 }, { 0xF824, 0x48C2 }, { 0xF826, 0x8C20 },
+		{ 0xF828, 0xC516 }, { 0xF82A, 0x64A4 }, { 0xF82C, 0x49C0 }, { 0xF82E, 0xF009 },
+		{ 0xF830, 0x74A2 }, { 0xF832, 0x8CA5 }, { 0xF834, 0x74A0 }, { 0xF836, 0xC50E },
+		{ 0xF838, 0x9CA2 }, { 0xF83A, 0x1C11 }, { 0xF83C, 0x9CA0 }, { 0xF83E, 0xE006 },
+		{ 0xF840, 0x74F8 }, { 0xF842, 0x48C4 }, { 0xF844, 0x8CF8 }, { 0xF846, 0xC404 },
+		{ 0xF848, 0xBC00 }, { 0xF84A, 0xC403 }, { 0xF84C, 0xBC00 }, { 0xF84E, 0x0BF2 },
+		{ 0xF850, 0x0C0A }, { 0xF852, 0xE434 }, { 0xF854, 0xD3C0 }, { 0xF856, 0x49D9 },
+		{ 0xF858, 0xF01F }, { 0xF85A, 0xC526 }, { 0xF85C, 0x64A5 }, { 0xF85E, 0x1400 },
+		{ 0xF860, 0xF007 }, { 0xF862, 0x0C01 }, { 0xF864, 0x8CA5 }, { 0xF866, 0x1C15 },
+		{ 0xF868, 0xC51B }, { 0xF86A, 0x9CA0 }, { 0xF86C, 0xE013 }, { 0xF86E, 0xC519 },
+		{ 0xF870, 0x74A0 }, { 0xF872, 0x48C4 }, { 0xF874, 0x8CA0 }, { 0xF876, 0xC516 },
+		{ 0xF878, 0x74A4 }, { 0xF87A, 0x48C8 }, { 0xF87C, 0x48CA }, { 0xF87E, 0x9CA4 },
+		{ 0xF880, 0xC512 }, { 0xF882, 0x1B00 }, { 0xF884, 0x9BA0 }, { 0xF886, 0x1B1C },
+		{ 0xF888, 0x483F }, { 0xF88A, 0x9BA2 }, { 0xF88C, 0x1B04 }, { 0xF88E, 0xC508 },
+		{ 0xF890, 0x9BA0 }, { 0xF892, 0xC505 }, { 0xF894, 0xBD00 }, { 0xF896, 0xC502 },
+		{ 0xF898, 0xBD00 }, { 0xF89A, 0x0300 }, { 0xF89C, 0x051E }, { 0xF89E, 0xE434 },
+		{ 0xF8A0, 0xE018 }, { 0xF8A2, 0xE092 }, { 0xF8A4, 0xDE20 }, { 0xF8A6, 0xD3C0 },
+		{ 0xF8A8, 0xC50F }, { 0xF8AA, 0x76A4 }, { 0xF8AC, 0x49E3 }, { 0xF8AE, 0xF007 },
+		{ 0xF8B0, 0x49C0 }, { 0xF8B2, 0xF103 }, { 0xF8B4, 0xC607 }, { 0xF8B6, 0xBE00 },
+		{ 0xF8B8, 0xC606 }, { 0xF8BA, 0xBE00 }, { 0xF8BC, 0xC602 }, { 0xF8BE, 0xBE00 },
+		{ 0xF8C0, 0x0C4C }, { 0xF8C2, 0x0C28 }, { 0xF8C4, 0x0C2C }, { 0xF8C6, 0xDC00 },
+		{ 0xF8C8, 0xC707 }, { 0xF8CA, 0x1D00 }, { 0xF8CC, 0x8DE2 }, { 0xF8CE, 0x48C1 },
+		{ 0xF8D0, 0xC502 }, { 0xF8D2, 0xBD00 }, { 0xF8D4, 0x00AA }, { 0xF8D6, 0xE0C0 },
+		{ 0xF8D8, 0xC502 }, { 0xF8DA, 0xBD00 }, { 0xF8DC, 0x0132 },
+	};
+
+	static const struct e_info_regdata final_seq[] = {
+		{ 0xFC2A, 0x0743 }, { 0xFC2C, 0x0801 }, { 0xFC2E, 0x0BE9 }, { 0xFC30, 0x02FD },
+		{ 0xFC32, 0x0C25 }, { 0xFC34, 0x00A9 }, { 0xFC36, 0x012D },
+	};
+
+	rtl_hw_start_8168g(tp);
 	rtl_ephy_init(tp, e_info_8411_2);
 
 	/* The following Realtek-provided magic fixes an issue with the RX unit
 	 * getting confused after the PHY having been powered-down.
 	 */
-	r8168_mac_ocp_write(tp, 0xFC28, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC2A, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC2C, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC2E, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC30, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC32, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC34, 0x0000);
-	r8168_mac_ocp_write(tp, 0xFC36, 0x0000);
+
+	r8168_mac_ocp_write_seq(tp, init_zero_seq);
 	mdelay(3);
 	r8168_mac_ocp_write(tp, 0xFC26, 0x0000);
 
-	r8168_mac_ocp_write(tp, 0xF800, 0xE008);
-	r8168_mac_ocp_write(tp, 0xF802, 0xE00A);
-	r8168_mac_ocp_write(tp, 0xF804, 0xE00C);
-	r8168_mac_ocp_write(tp, 0xF806, 0xE00E);
-	r8168_mac_ocp_write(tp, 0xF808, 0xE027);
-	r8168_mac_ocp_write(tp, 0xF80A, 0xE04F);
-	r8168_mac_ocp_write(tp, 0xF80C, 0xE05E);
-	r8168_mac_ocp_write(tp, 0xF80E, 0xE065);
-	r8168_mac_ocp_write(tp, 0xF810, 0xC602);
-	r8168_mac_ocp_write(tp, 0xF812, 0xBE00);
-	r8168_mac_ocp_write(tp, 0xF814, 0x0000);
-	r8168_mac_ocp_write(tp, 0xF816, 0xC502);
-	r8168_mac_ocp_write(tp, 0xF818, 0xBD00);
-	r8168_mac_ocp_write(tp, 0xF81A, 0x074C);
-	r8168_mac_ocp_write(tp, 0xF81C, 0xC302);
-	r8168_mac_ocp_write(tp, 0xF81E, 0xBB00);
-	r8168_mac_ocp_write(tp, 0xF820, 0x080A);
-	r8168_mac_ocp_write(tp, 0xF822, 0x6420);
-	r8168_mac_ocp_write(tp, 0xF824, 0x48C2);
-	r8168_mac_ocp_write(tp, 0xF826, 0x8C20);
-	r8168_mac_ocp_write(tp, 0xF828, 0xC516);
-	r8168_mac_ocp_write(tp, 0xF82A, 0x64A4);
-	r8168_mac_ocp_write(tp, 0xF82C, 0x49C0);
-	r8168_mac_ocp_write(tp, 0xF82E, 0xF009);
-	r8168_mac_ocp_write(tp, 0xF830, 0x74A2);
-	r8168_mac_ocp_write(tp, 0xF832, 0x8CA5);
-	r8168_mac_ocp_write(tp, 0xF834, 0x74A0);
-	r8168_mac_ocp_write(tp, 0xF836, 0xC50E);
-	r8168_mac_ocp_write(tp, 0xF838, 0x9CA2);
-	r8168_mac_ocp_write(tp, 0xF83A, 0x1C11);
-	r8168_mac_ocp_write(tp, 0xF83C, 0x9CA0);
-	r8168_mac_ocp_write(tp, 0xF83E, 0xE006);
-	r8168_mac_ocp_write(tp, 0xF840, 0x74F8);
-	r8168_mac_ocp_write(tp, 0xF842, 0x48C4);
-	r8168_mac_ocp_write(tp, 0xF844, 0x8CF8);
-	r8168_mac_ocp_write(tp, 0xF846, 0xC404);
-	r8168_mac_ocp_write(tp, 0xF848, 0xBC00);
-	r8168_mac_ocp_write(tp, 0xF84A, 0xC403);
-	r8168_mac_ocp_write(tp, 0xF84C, 0xBC00);
-	r8168_mac_ocp_write(tp, 0xF84E, 0x0BF2);
-	r8168_mac_ocp_write(tp, 0xF850, 0x0C0A);
-	r8168_mac_ocp_write(tp, 0xF852, 0xE434);
-	r8168_mac_ocp_write(tp, 0xF854, 0xD3C0);
-	r8168_mac_ocp_write(tp, 0xF856, 0x49D9);
-	r8168_mac_ocp_write(tp, 0xF858, 0xF01F);
-	r8168_mac_ocp_write(tp, 0xF85A, 0xC526);
-	r8168_mac_ocp_write(tp, 0xF85C, 0x64A5);
-	r8168_mac_ocp_write(tp, 0xF85E, 0x1400);
-	r8168_mac_ocp_write(tp, 0xF860, 0xF007);
-	r8168_mac_ocp_write(tp, 0xF862, 0x0C01);
-	r8168_mac_ocp_write(tp, 0xF864, 0x8CA5);
-	r8168_mac_ocp_write(tp, 0xF866, 0x1C15);
-	r8168_mac_ocp_write(tp, 0xF868, 0xC51B);
-	r8168_mac_ocp_write(tp, 0xF86A, 0x9CA0);
-	r8168_mac_ocp_write(tp, 0xF86C, 0xE013);
-	r8168_mac_ocp_write(tp, 0xF86E, 0xC519);
-	r8168_mac_ocp_write(tp, 0xF870, 0x74A0);
-	r8168_mac_ocp_write(tp, 0xF872, 0x48C4);
-	r8168_mac_ocp_write(tp, 0xF874, 0x8CA0);
-	r8168_mac_ocp_write(tp, 0xF876, 0xC516);
-	r8168_mac_ocp_write(tp, 0xF878, 0x74A4);
-	r8168_mac_ocp_write(tp, 0xF87A, 0x48C8);
-	r8168_mac_ocp_write(tp, 0xF87C, 0x48CA);
-	r8168_mac_ocp_write(tp, 0xF87E, 0x9CA4);
-	r8168_mac_ocp_write(tp, 0xF880, 0xC512);
-	r8168_mac_ocp_write(tp, 0xF882, 0x1B00);
-	r8168_mac_ocp_write(tp, 0xF884, 0x9BA0);
-	r8168_mac_ocp_write(tp, 0xF886, 0x1B1C);
-	r8168_mac_ocp_write(tp, 0xF888, 0x483F);
-	r8168_mac_ocp_write(tp, 0xF88A, 0x9BA2);
-	r8168_mac_ocp_write(tp, 0xF88C, 0x1B04);
-	r8168_mac_ocp_write(tp, 0xF88E, 0xC508);
-	r8168_mac_ocp_write(tp, 0xF890, 0x9BA0);
-	r8168_mac_ocp_write(tp, 0xF892, 0xC505);
-	r8168_mac_ocp_write(tp, 0xF894, 0xBD00);
-	r8168_mac_ocp_write(tp, 0xF896, 0xC502);
-	r8168_mac_ocp_write(tp, 0xF898, 0xBD00);
-	r8168_mac_ocp_write(tp, 0xF89A, 0x0300);
-	r8168_mac_ocp_write(tp, 0xF89C, 0x051E);
-	r8168_mac_ocp_write(tp, 0xF89E, 0xE434);
-	r8168_mac_ocp_write(tp, 0xF8A0, 0xE018);
-	r8168_mac_ocp_write(tp, 0xF8A2, 0xE092);
-	r8168_mac_ocp_write(tp, 0xF8A4, 0xDE20);
-	r8168_mac_ocp_write(tp, 0xF8A6, 0xD3C0);
-	r8168_mac_ocp_write(tp, 0xF8A8, 0xC50F);
-	r8168_mac_ocp_write(tp, 0xF8AA, 0x76A4);
-	r8168_mac_ocp_write(tp, 0xF8AC, 0x49E3);
-	r8168_mac_ocp_write(tp, 0xF8AE, 0xF007);
-	r8168_mac_ocp_write(tp, 0xF8B0, 0x49C0);
-	r8168_mac_ocp_write(tp, 0xF8B2, 0xF103);
-	r8168_mac_ocp_write(tp, 0xF8B4, 0xC607);
-	r8168_mac_ocp_write(tp, 0xF8B6, 0xBE00);
-	r8168_mac_ocp_write(tp, 0xF8B8, 0xC606);
-	r8168_mac_ocp_write(tp, 0xF8BA, 0xBE00);
-	r8168_mac_ocp_write(tp, 0xF8BC, 0xC602);
-	r8168_mac_ocp_write(tp, 0xF8BE, 0xBE00);
-	r8168_mac_ocp_write(tp, 0xF8C0, 0x0C4C);
-	r8168_mac_ocp_write(tp, 0xF8C2, 0x0C28);
-	r8168_mac_ocp_write(tp, 0xF8C4, 0x0C2C);
-	r8168_mac_ocp_write(tp, 0xF8C6, 0xDC00);
-	r8168_mac_ocp_write(tp, 0xF8C8, 0xC707);
-	r8168_mac_ocp_write(tp, 0xF8CA, 0x1D00);
-	r8168_mac_ocp_write(tp, 0xF8CC, 0x8DE2);
-	r8168_mac_ocp_write(tp, 0xF8CE, 0x48C1);
-	r8168_mac_ocp_write(tp, 0xF8D0, 0xC502);
-	r8168_mac_ocp_write(tp, 0xF8D2, 0xBD00);
-	r8168_mac_ocp_write(tp, 0xF8D4, 0x00AA);
-	r8168_mac_ocp_write(tp, 0xF8D6, 0xE0C0);
-	r8168_mac_ocp_write(tp, 0xF8D8, 0xC502);
-	r8168_mac_ocp_write(tp, 0xF8DA, 0xBD00);
-	r8168_mac_ocp_write(tp, 0xF8DC, 0x0132);
+	r8168_mac_ocp_write_seq(tp, recover_seq);
 
 	r8168_mac_ocp_write(tp, 0xFC26, 0x8000);
 
-	r8168_mac_ocp_write(tp, 0xFC2A, 0x0743);
-	r8168_mac_ocp_write(tp, 0xFC2C, 0x0801);
-	r8168_mac_ocp_write(tp, 0xFC2E, 0x0BE9);
-	r8168_mac_ocp_write(tp, 0xFC30, 0x02FD);
-	r8168_mac_ocp_write(tp, 0xFC32, 0x0C25);
-	r8168_mac_ocp_write(tp, 0xFC34, 0x00A9);
-	r8168_mac_ocp_write(tp, 0xFC36, 0x012D);
+	r8168_mac_ocp_write_seq(tp, final_seq);
+
 }
 
 static void rtl_hw_start_8168h_1(struct rtl8169_private *tp)
-- 
2.34.1