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X-CSE-ConnectionGUID: UqaeKbMIQxSly8xXodAGCg== X-CSE-MsgGUID: aGn5afrjTx2ahTWZmwgj+A== X-IronPort-AV: E=McAfee;i="6800,10657,11587"; a="88537926" X-IronPort-AV: E=Sophos;i="6.19,242,1754982000"; d="scan'208";a="88537926" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2025 03:30:01 -0700 X-CSE-ConnectionGUID: zWABuonbRbS1ip2ImfbO1g== X-CSE-MsgGUID: RU7DY4gOTKKSh/QSk7sUCg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,242,1754982000"; d="scan'208";a="183707922" Received: from black.igk.intel.com ([10.91.253.5]) by fmviesa008.fm.intel.com with ESMTP; 20 Oct 2025 03:29:59 -0700 Received: by black.igk.intel.com (Postfix, from userid 1001) id 67B9895; Mon, 20 Oct 2025 12:29:58 +0200 (CEST) Date: Mon, 20 Oct 2025 12:29:58 +0200 From: Mika Westerberg To: Jinhui Guo Cc: andriy.shevchenko@linux.intel.com, jsd@semihalf.com, andi.shyti@kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] i2c: designware: Disable SMBus interrupts to prevent storms from mis-configured firmware Message-ID: <20251020102958.GL2912318@black.igk.intel.com> References: <20251011073057.2959-1-guojinhui.liam@bytedance.com> <20251011073057.2959-2-guojinhui.liam@bytedance.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251011073057.2959-2-guojinhui.liam@bytedance.com> Hi, On Sat, Oct 11, 2025 at 03:30:57PM +0800, Jinhui Guo wrote: > When probing the I2C master, disable SMBus interrupts to prevent > storms caused by broken firmware mis-configuring IC_SMBUS=1; the > handler never services them and a mis-configured SMBUS Master > extend-clock timeout can flood the CPU. > > Signed-off-by: Jinhui Guo > --- > drivers/i2c/busses/i2c-designware-core.h | 1 + > drivers/i2c/busses/i2c-designware-master.c | 11 +++++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h > index 347843b4f5dd..d1122ff0a1b7 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*" == v1.11* */ > diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c > index c7a72c28786c..eeb60536da32 100644 > --- a/drivers/i2c/busses/i2c-designware-master.c > +++ b/drivers/i2c/busses/i2c-designware-master.c > @@ -997,6 +997,11 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev) > return 0; > } > > +static inline void i2c_dw_disable_smbus_intr(struct dw_i2c_dev *dev) > +{ > + regmap_write(dev->map, DW_IC_SMBUS_INTR_MASK, 0); > +} I wonder instead of this wrapper, can you just do this in i2c_dw_init_master() right after the adapter has been disabled? > + > int i2c_dw_probe_master(struct dw_i2c_dev *dev) > { > struct i2c_adapter *adap = &dev->adapter; > @@ -1063,6 +1068,12 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev) > return ret; > > __i2c_dw_write_intr_mask(dev, 0); > + /* > + * Mask SMBus interrupts to block storms from broken > + * firmware that leaves IC_SMBUS=1; the handler never > + * services them. > + */ > + i2c_dw_disable_smbus_intr(dev); > i2c_dw_release_lock(dev); > > if (!(dev->flags & ACCESS_POLLING)) { > -- > 2.20.1