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Tue, 21 Oct 2025 00:57:32 -0700 (PDT) From: Jinhui Guo To: mika.westerberg@linux.intel.com, andriy.shevchenko@linux.intel.com, jsd@semihalf.com, andi.shyti@kernel.org Cc: guojinhui.liam@bytedance.com, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/1] i2c: designware: Disable SMBus interrupts to prevent storms from mis-configured firmware Date: Tue, 21 Oct 2025 15:57:14 +0800 Message-Id: <20251021075714.3712-2-guojinhui.liam@bytedance.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20251021075714.3712-1-guojinhui.liam@bytedance.com> References: <20251021075714.3712-1-guojinhui.liam@bytedance.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" When probing the I2C master, disable SMBus interrupts to prevent storms caused by broken firmware mis-configuring IC_SMBUS=3D1; the handler never services them and a mis-configured SMBUS Master extend-clock timeout or SMBUS Slave extend-clock timeout can flood the CPU. Signed-off-by: Jinhui Guo Reviewed-by: Andy Shevchenko Acked-by: Mika Westerberg --- drivers/i2c/busses/i2c-designware-core.h | 1 + drivers/i2c/busses/i2c-designware-master.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/= i2c-designware-core.h index 347843b4f5dd..436555543c79 100644 --- a/drivers/i2c/busses/i2c-designware-core.h +++ b/drivers/i2c/busses/i2c-designware-core.h @@ -78,6 +78,7 @@ #define DW_IC_TX_ABRT_SOURCE 0x80 #define DW_IC_ENABLE_STATUS 0x9c #define DW_IC_CLR_RESTART_DET 0xa8 +#define DW_IC_SMBUS_INTR_MASK 0xcc #define DW_IC_COMP_PARAM_1 0xf4 #define DW_IC_COMP_VERSION 0xf8 #define DW_IC_SDA_HOLD_MIN_VERS 0x3131312A /* "111*" =3D=3D v1.11* */ diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busse= s/i2c-designware-master.c index 41e9b5ecad20..45bfca05bb30 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -220,6 +220,13 @@ static int i2c_dw_init_master(struct dw_i2c_dev *dev) /* Disable the adapter */ __i2c_dw_disable(dev); =20 + /* + * Mask SMBus interrupts to block storms from broken + * firmware that leaves IC_SMBUS=3D1; the handler never + * services them. + */ + regmap_write(dev->map, DW_IC_SMBUS_INTR_MASK, 0); + /* Write standard speed timing parameters */ regmap_write(dev->map, DW_IC_SS_SCL_HCNT, dev->ss_hcnt); regmap_write(dev->map, DW_IC_SS_SCL_LCNT, dev->ss_lcnt); --=20 2.20.1