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clocksource: mips-gic-timer: fix clocksource counter width

PATCH New Felix Fietkau 2 participants 2 messages Feb 28, 2018

Subsystems (2)
Clocksource, clockevent drivers MIPS core drivers
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Felix Fietkau

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#0 lore raw

PATCH v2 1/1 clocksource: mips-gic-timer: fix clocksource counter width

This code is trying to extract the GIC_CONFIG_COUNTBITS field from read_gic_config(), so it needs to shift count_width right by the index of the least significant bit (__ffs) instead of the most significant bit (__fls) of the field mask.

Fixes e07127a077c7 ("clocksource: mips-gic-timer: Use new GIC accessor functions")
Cc Paul Burton <[email protected]>
Cc [email protected]
Signed-off-by Felix Fietkau <[email protected]>
---
 drivers/clocksource/mips-gic-timer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/clocksource/mips-gic-timer.c +1 -1
index a04808a21d4e..bf0eee78c6ef 100644
@@ -166,7 +166,7 @@ static int __init __gic_clocksource_init(void)
 
 	/* Set clocksource mask. */
 	count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
-	count_width >>= __fls(GIC_CONFIG_COUNTBITS);
+	count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
 	count_width *= 4;
 	count_width += 32;
 	gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);
Signature · 1 line
2.14.2
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#1 lore raw

[tip:timers/urgent] clocksource/drivers/mips-gic-timer: Use correct shift count to extract data

clocksource/drivers/mips-gic-timer: Use correct shift count to extract data
Commit-ID:  5753405e27f8fe4c42c1537d3ddbd9e058e54cdc
Gitweb:     https://git.kernel.org/tip/5753405e27f8fe4c42c1537d3ddbd9e058e54cdc
Author:     Felix Fietkau <[email protected]>
AuthorDate: Wed, 28 Feb 2018 10:56:10 +0100
Committer:  Thomas Gleixner <[email protected]>
CommitDate: Wed, 28 Feb 2018 13:55:14 +0100

clocksource/drivers/mips-gic-timer: Use correct shift count to extract data

__gic_clocksource_init() extracts the GIC_CONFIG_COUNTBITS field from read_gic_config() by right shifting the register value. The shift count is determined by the most significant bit (__fls) of the bitmask which is wrong as it shifts out the complete bitfield.

Use the least significant bit (__ffs) instead to shift the bitfield down to bit 0.

Fixes e07127a077c7 ("clocksource: mips-gic-timer: Use new GIC accessor functions")
Signed-off-by Felix Fietkau <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Cc [email protected]
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here
---
 drivers/clocksource/mips-gic-timer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/clocksource/mips-gic-timer.c +1 -1
index 65e18c86d9b9..986b6796b631 100644
@@ -166,7 +166,7 @@ static int __init __gic_clocksource_init(void)
 
 	/* Set clocksource mask. */
 	count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
-	count_width >>= __fls(GIC_CONFIG_COUNTBITS);
+	count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
 	count_width *= 4;
 	count_width += 32;
 	gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);