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Commit c69fa3b7 authored by Ondrej Jirman's avatar Ondrej Jirman Committed by Greg Kroah-Hartman
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i2c: rk3x: Handle a spurious start completion interrupt flag 



[ Upstream commit 02fe0fbd8a21e183687925c3a266ae27dda9840f ]

In a typical read transfer, start completion flag is being set after
read finishes (notice ipd bit 4 being set):

trasnfer poll=0
i2c start
rk3x-i2c fdd40000.i2c: IRQ: state 1, ipd: 10
i2c read
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 1b
i2c stop
rk3x-i2c fdd40000.i2c: IRQ: state 4, ipd: 33

This causes I2C transfer being aborted in polled mode from a stop completion
handler:

trasnfer poll=1
i2c start
rk3x-i2c fdd40000.i2c: IRQ: state 1, ipd: 10
i2c read
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 0
rk3x-i2c fdd40000.i2c: IRQ: state 2, ipd: 1b
i2c stop
rk3x-i2c fdd40000.i2c: IRQ: state 4, ipd: 13
i2c stop
rk3x-i2c fdd40000.i2c: unexpected irq in STOP: 0x10

Clearing the START flag after read fixes the issue without any obvious
side effects.

This issue was dicovered on RK3566 when adding support for powering
off the RK817 PMIC.

Signed-off-by: default avatarOndrej Jirman <megous@megous.com>
Reviewed-by: default avatarJohn Keeping <john@metanate.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 3125c97a

drivers/i2c/busses/i2c-rk3x.c

+2 −2
Original line number Diff line number Diff line
@@ -325,8 +325,8 @@ static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd) 
	if (!(ipd & REG_INT_MBRF))

		return;



	/* ack interrupt */

	i2c_writel(i2c, REG_INT_MBRF, REG_IPD);

	/* ack interrupt (read also produces a spurious START flag, clear it too) */

	i2c_writel(i2c, REG_INT_MBRF | REG_INT_START, REG_IPD);



	/* Can only handle a maximum of 32 bytes at a time */

	if (len > 32)