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From:   YE Chengfeng <cyeaa@connect.ust.hk>
To:     "andi.shyti@kernel.org" <andi.shyti@kernel.org>,
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CC:     "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
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        <bcm-kernel-feedback-list@broadcom.com>
Subject: [PATCH] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue
Thread-Topic: [PATCH] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue
Thread-Index: AQHZptF4vW+xYGiqv0K3I948JeZ3Og==
Date:   Sat, 24 Jun 2023 19:36:02 +0000
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iproc_i2c_rd_reg and iproc_i2c_wr_reg are called from both=0A=
interrupt context (e.g. bcm_iproc_i2c_isr) and process context=0A=
(e.g. bcm_iproc_i2c_suspend). Therefore, interrupts should be=0A=
disabled to avoid potential deadlock. To prevent this deadlock,=0A=
use spin_lock_irqsave.=0A=
=0A=
Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>=0A=
---=0A=
=A0drivers/i2c/busses/i2c-bcm-iproc.c | 10 ++++++----=0A=
=A01 file changed, 6 insertions(+), 4 deletions(-)=0A=
=0A=
diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bc=
m-iproc.c=0A=
index 85d8a6b04885..d02245e4db8c 100644=0A=
--- a/drivers/i2c/busses/i2c-bcm-iproc.c=0A=
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c=0A=
@@ -233,13 +233,14 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i=
2c_dev *iproc_i2c,=0A=
=A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 u32 =
offset)=0A=
=A0{=0A=
=A0 =A0 =A0 =A0 u32 val;=0A=
+ =A0 =A0 =A0 unsigned long flags;=0A=
=0A=
=A0 =A0 =A0 =A0 if (iproc_i2c->idm_base) {=0A=
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock(&iproc_i2c->idm_lock);=0A=
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock_irqsave(&iproc_i2c->idm_lock, flags=
);=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 writel(iproc_i2c->ape_addr_mask,=0A=
=A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 iproc_i2c->idm_base + IDM_CT=
RL_DIRECT_OFFSET);=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 val =3D readl(iproc_i2c->base + offset);=0A=
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&iproc_i2c->idm_lock);=0A=
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock_irqrestore(&iproc_i2c->idm_lock, =
flags);=0A=
=A0 =A0 =A0 =A0 } else {=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 val =3D readl(iproc_i2c->base + offset);=0A=
=A0 =A0 =A0 =A0 }=0A=
@@ -250,12 +251,13 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i=
2c_dev *iproc_i2c,=0A=
=A0static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c,=
=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 u32=
 offset, u32 val)=0A=
=A0{=0A=
+ =A0 =A0 =A0 unsigned long flags;=0A=
=A0 =A0 =A0 =A0 if (iproc_i2c->idm_base) {=0A=
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock(&iproc_i2c->idm_lock);=0A=
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock_irqsave(&iproc_i2c->idm_lock, flags=
);=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 writel(iproc_i2c->ape_addr_mask,=0A=
=A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 iproc_i2c->idm_base + IDM_CT=
RL_DIRECT_OFFSET);=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 writel(val, iproc_i2c->base + offset);=0A=
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&iproc_i2c->idm_lock);=0A=
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock_irqrestore(&iproc_i2c->idm_lock, =
flags);=0A=
=A0 =A0 =A0 =A0 } else {=0A=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 writel(val, iproc_i2c->base + offset);=0A=
=A0 =A0 =A0 =A0 }=0A=
--=A0=0A=
2.17.1=0A=