linux-kernel - [PATCH 4.0 21/72] Revert "MIPS: Avoid pipeline stalls on some MIPS32R2 cores."

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Date:	Mon, 11 May 2015 10:54:27 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 4.0 21/72] Revert "MIPS: Avoid pipeline stalls on some MIPS32R2 cores."

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------


Commit 9eaffa84a8a46adab065c983401fc9d5949c958f upstream.

For a discussion, see http://patchwork.linux-mips.org/patch/9539/.

This reverts commit 625c0a21700bdb90844d926a1508a17a77e369c9.

Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/mips/mm/tlbex.c |   21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -501,26 +501,9 @@ static void build_tlb_write_entry(u32 **
 	case tlb_indexed: tlbw = uasm_i_tlbwi; break;
 	}
 
-	if (cpu_has_mips_r2_exec_hazard) {
-		/*
-		 * The architecture spec says an ehb is required here,
-		 * but a number of cores do not have the hazard and
-		 * using an ehb causes an expensive pipeline stall.
-		 */
-		switch (current_cpu_type()) {
-		case CPU_M14KC:
-		case CPU_74K:
-		case CPU_1074K:
-		case CPU_PROAPTIV:
-		case CPU_P5600:
-		case CPU_M5150:
-		case CPU_QEMU_GENERIC:
-			break;
-
-		default:
+	if (cpu_has_mips_r2_r6) {
+		if (cpu_has_mips_r2_exec_hazard)
 			uasm_i_ehb(p);
-			break;
-		}
 		tlbw(p);
 		return;
 	}


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