From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yadi <yadi.hu@windriver.com>
Subject: Re: RESEND:i2c-eg20t: fix race between i2c init and interrupt enable
Date: Mon, 12 Sep 2016 08:41:38 +0800
Message-ID: <57D5F9C2.5060107@windriver.com>
References: <1473240337-5694-1-git-send-email-yadi.hu@windriver.com>
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ping....  any objection?

Yadi


On 2016年09月07日 17:25, Yadi Hu wrote:
> the eg20t driver call request_irq() function before the pch_base_address,
> base address of i2c controller's register, isassigned an effective value.
>
> it is one possible scenario that an interrupt which isn't inside eg20t
> arrives immediately after request_irq() is executed when i2c controller
> shares an interrupt number with others.  since the interrupt handler
> pch_i2c_handler() has already active as shared action, it will be called
> and read its own register to determine if this interrupt is from itself.
>
> At that moment, since base address of i2c registers is not remapped
> in kernel space yet,so the INT handler will access an illegal address
> and then a error occurs.
>
> Bad IO access at port 0x18 (return inl(port))
>   Call Trace:
>    [<c102c733>] warn_slowpath_common+0x73/0xa0
>    [<c13109f5>] ? bad_io_access+0x45/0x50
>    [<c13109f5>] ? bad_io_access+0x45/0x50
>    [<c102c804>] warn_slowpath_fmt+0x34/0x40
>    [<c13109f5>] bad_io_access+0x45/0x50
>    [<c1310b62>] ioread32+0x22/0x40
>    [<c14c60db>] pch_i2c_handler+0x3b/0x120
>    [<c1092f34>] handle_irq_event_percpu+0x64/0x330
>    [<c109323b>] handle_irq_event+0x3b/0x60
>    [<c1095b50>] ? unmask_irq+0x30/0x30
>    [<c1095ba0>] handle_fasteoi_irq+0x50/0xe0
>    <IRQ>  [<c16e7e78>] ? do_IRQ+0x48/0xc0
>    [<c16e7f6f>] ? smp_apic_timer_interrupt+0x7f/0x17a
>    [<c16e7da9>] ? common_interrupt+0x29/0x30
>    [<c1008ebb>] ? mwait_idle+0x8b/0x2c0
>    [<c1009e8e>] ? cpu_idle+0x9e/0xc0
>    [<c16be408>] ? rest_init+0x6c/0x74
>    [<c19f770a>] ? start_kernel+0x311/0x318
>    [<c19f7231>] ? repair_env_string+0x51/0x51
>    [<c19f7078>] ? i386_start_kernel+0x78/0x7d
>   ---[ end trace eb3a1028f468a140 ]---
>   i2c_eg20t 0000:05:0c.2: pch_i2c_handler :I2C-3 mode(0) is not supported
>
> after testing last patch, replacing request_irq() location is not a
> good idea,it might produce a little time windows ,in which the interrupts
> occurring inside  will be omitted.
>
> the new patch adds a check point on interrupt handler in case field
> 'pch_base_address' has not been initialed.
>
>
> Yadi Hu (1)
>      i2c-eg20t: fix race between i2c init and interrupt enable
>
> drivers/i2c/busses/i2c-eg20t.c |    5 +++++
>   1 file changed, 5 insertions(+)
>