linux-kernel - [PATCH] MIPS: Revert "add support for buggy MT7621S core detection"

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Date:   Thu, 30 Sep 2021 09:57:41 -0700
From:   Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sergio Paracuellos <sergio.paracuellos@...il.com>,
        Greg Ungerer <gerg@...nel.org>,
        Strontium <strntydog@...il.com>,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Felix Fietkau <nbd@....name>
Subject: [PATCH] MIPS: Revert "add support for buggy MT7621S core detection"

This reverts commit 6decd1aad15f56b169217789630a0098b496de0e. CPULAUNCH
register is not set properly by some bootloaders, causing a regression
until a bootloader change is made, which is hard if not impossible on
some embedded devices. Revert the change until a more robust core
detection mechanism that works on MT7621S routers such as Netgear R6220
as well as platforms like Digi EX15 can be made.

Link: https://lore.kernel.org/lkml/4d9e3b39-7caa-d372-5d7b-42dcec36fec7@kernel.org
Fixes: 6decd1aad15f ("MIPS: add support for buggy MT7621S core detection")
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
---
 arch/mips/include/asm/mips-cps.h | 23 +----------------------
 1 file changed, 1 insertion(+), 22 deletions(-)

diff --git a/arch/mips/include/asm/mips-cps.h b/arch/mips/include/asm/mips-cps.h
index 35fb8ee6dd33..fd43d876892e 100644
--- a/arch/mips/include/asm/mips-cps.h
+++ b/arch/mips/include/asm/mips-cps.h
@@ -10,8 +10,6 @@
 #include <linux/io.h>
 #include <linux/types.h>
 
-#include <asm/mips-boards/launch.h>
-
 extern unsigned long __cps_access_bad_size(void)
 	__compiletime_error("Bad size for CPS accessor");
 
@@ -167,30 +165,11 @@ static inline uint64_t mips_cps_cluster_config(unsigned int cluster)
  */
 static inline unsigned int mips_cps_numcores(unsigned int cluster)
 {
-	unsigned int ncores;
-
 	if (!mips_cm_present())
 		return 0;
 
 	/* Add one before masking to handle 0xff indicating no cores */
-	ncores = (mips_cps_cluster_config(cluster) + 1) & CM_GCR_CONFIG_PCORES;
-
-	if (IS_ENABLED(CONFIG_SOC_MT7621)) {
-		struct cpulaunch *launch;
-
-		/*
-		 * Ralink MT7621S SoC is single core, but the GCR_CONFIG method
-		 * always reports 2 cores. Check the second core's LAUNCH_FREADY
-		 * flag to detect if the second core is missing. This method
-		 * only works before the core has been started.
-		 */
-		launch = (struct cpulaunch *)CKSEG0ADDR(CPULAUNCH);
-		launch += 2; /* MT7621 has 2 VPEs per core */
-		if (!(launch->flags & LAUNCH_FREADY))
-			ncores = 1;
-	}
-
-	return ncores;
+	return (mips_cps_cluster_config(cluster) + 1) & CM_GCR_CONFIG_PCORES;
 }
 
 /**
-- 
2.33.0