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Commit 72c70f01 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
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MIPS: Stop setting I6400 FTLBP 



The FTLBP field in Config7 for the I6400 is intended as chicken bits for
debugging rather than as a field that software actually makes use of.
For best performance, FTLBP should be left at its default value of 0
with all TLB writes hitting the FTLB by default.

Additionally, since set_ftlb_enable is called from decode_configs before
decode_config4 which determines the size of the TLBs, this was
previously always setting FTLBP=3 for a 3:1 FTLB:VTLB write ratio which
makes abysmal use of the available FTLB resources.

This effectively reverts b0c4e1b79d8a ("MIPS: Set up FTLB probability
for I6400").

Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
Fixes: b0c4e1b79d8a ("MIPS: Set up FTLB probability for I6400")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14021/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 3021773c

arch/mips/include/asm/mipsregs.h

+0 −2
Original line number Diff line number Diff line
@@ -660,8 +660,6 @@ 


#define MIPS_CONF7_IAR		(_ULCAST_(1) << 10)

#define MIPS_CONF7_AR		(_ULCAST_(1) << 16)

/* FTLB probability bits for R6 */

#define MIPS_CONF7_FTLBP_SHIFT	(18)



/* WatchLo* register definitions */

#define MIPS_WATCHLO_IRW	(_ULCAST_(0x7) << 0)

arch/mips/kernel/cpu-probe.c

+2 −7
Original line number Diff line number Diff line
@@ -555,13 +555,8 @@ static int set_ftlb_enable(struct cpuinfo_mips *c, int enable) 
			write_c0_config6(config &  ~MIPS_CONF6_FTLBEN);

		break;

	case CPU_I6400:

		/* I6400 & related cores use Config7 to configure FTLB */

		config = read_c0_config7();

		/* Clear the old probability value */

		config &= ~(3 << MIPS_CONF7_FTLBP_SHIFT);

		write_c0_config7(config | (calculate_ftlb_probability(c)

					   << MIPS_CONF7_FTLBP_SHIFT));

		break;

		/* There's no way to disable the FTLB */

		return !enable;

	case CPU_LOONGSON3:

		/* Flush ITLB, DTLB, VTLB and FTLB */

		write_c0_diag(LOONGSON_DIAG_ITLB | LOONGSON_DIAG_DTLB |