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From:   Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
To:     Jason Gunthorpe <jgg@ziepe.ca>, Joerg Roedel <jroedel@suse.de>,
        Lu Baolu <baolu.lu@linux.intel.com>, iommu@lists.linux.dev,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Cc:     Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Heiner Kallweit <hkallweit1@gmail.com>, nic_swsd@realtek.com,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>,
        Marco Elver <elver@google.com>
Subject: [PATCH v4 2/5] r8169: Coalesce RTL8411b PHY power-down recovery calls to reduce spinlock stalls
Date:   Sun, 29 Oct 2023 12:04:41 +0100
Message-Id: <20231029110442.347448-2-mirsad.todorovac@alu.unizg.hr>
In-Reply-To: <20231029110442.347448-1-mirsad.todorovac@alu.unizg.hr>
References: <20231029110442.347448-1-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 and CPUs on the same memory controller
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:

    static void rtl_hw_start_8411_2(struct rtl8169_private *tp)
    {

	...

	/* The following Realtek-provided magic fixes an issue with the RX unit
	 * getting confused after the PHY having been powered-down.
	 */

	static const struct recover_8411b_info init_zero_seq[] = {
	    { 0xFC28, 0x0000 }, { 0xFC2A, 0x0000 }, { 0xFC2C, 0x0000 },
	    ...
	};

	static const struct recover_8411b_info recover_seq[] = {
	    { 0xF800, 0xE008 }, { 0xF802, 0xE00A }, { 0xF804, 0xE00C },
	    ...
	};

	static const struct recover_8411b_info final_seq[] = {
	    { 0xFC2A, 0x0743 }, { 0xFC2C, 0x0801 }, { 0xFC2E, 0x0BE9 },
	    ...
	};

	r8168_mac_ocp_write_seq(tp, init_zero_seq);
	mdelay(3);
	r8168_mac_ocp_write(tp, 0xFC26, 0x0000);
	r8168_mac_ocp_write_seq(tp, recover_seq);
	r8168_mac_ocp_write(tp, 0xFC26, 0x8000);
	r8168_mac_ocp_write_seq(tp, final_seq);
    }

The hex data is preserved intact through s/r8168_mac_ocp_write[(]tp,/{ / and s/[)];/ },/
functions that only changed the function names and the ending of the line, so the actual
hex data is unchanged.

Note that the reason for the introduction of the original commit
was to enable recovery of the RX unit on the RTL8411b which was confused by the
powered-down PHY. This sequence of r8168_mac_ocp_write() calls amplifies the problem
into a series of about 500+ memory bus locks, most waiting for the main MMIO memory
read-modify-write under a LOCK. The memory barrier in RTL_W32 should suffice for
the programming sequence to reach RTL NIC registers.

[0] https://bugzilla.redhat.com/show_bug.cgi?id=1692075

Fixes: fe4e8db0392a6 ("r8169: fix issue with confused RX unit after PHY power-down on RTL8411b")
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>
---
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 df79fd95cf2d..3dae924a6ca3 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