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BACKPORT: i2c: rk3x: Handle a spurious start completion interrupt flag

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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: Ondrej Jirman <megous@megous.com>
Reviewed-by: John Keeping <john@metanate.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
(cherry picked from commit 02fe0fbd8a)
Signed-off-by: David Wu <david.wu@rock-chips.com>
Change-Id: I9cf23d9a9bc9560a421c6fe13a82a6637d8a1432
This commit is contained in:
Ondrej Jirman
2021-09-24 13:15:27 +02:00
committed by Tao Huang
parent 0260220515
commit 7c62ae6c44
1 changed files with 2 additions and 2 deletions
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4
drivers/i2c/busses/i2c-rk3x.c
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@@ -519,8 +519,8 @@ 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);
/* read the data from receive buffer */
rk3x_i2c_read(i2c);