netdev - RE: [PATCH net 0/3] Add I2C bus lock for Wangxun

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Message-ID: <01d701daf75c$50db4450$f291ccf0$@trustnetic.com>
Date: Mon, 26 Aug 2024 10:04:42 +0800
From: Jiawen Wu <jiawenwu@...stnetic.com>
To: "'Andrew Lunn'" <andrew@...n.ch>
Cc: <andi.shyti@...nel.org>,
	<jarkko.nikula@...ux.intel.com>,
	<andriy.shevchenko@...ux.intel.com>,
	<mika.westerberg@...ux.intel.com>,
	<jsd@...ihalf.com>,
	<davem@...emloft.net>,
	<edumazet@...gle.com>,
	<kuba@...nel.org>,
	<pabeni@...hat.com>,
	<rmk+kernel@...linux.org.uk>,
	<piotr.raczynski@...el.com>,
	<linux-i2c@...r.kernel.org>,
	<netdev@...r.kernel.org>,
	<mengyuanlou@...-swift.com>,
	<duanqiangwen@...-swift.com>
Subject: RE: [PATCH net 0/3] Add I2C bus lock for Wangxun

On Mon, Aug 26, 2024 9:33 AM, Andrew Lunn wrote:
> On Fri, Aug 23, 2024 at 11:02:39AM +0800, Jiawen Wu wrote:
> > Sometimes the driver can not get the SFP information because the I2C bus
> > is accessed by the firmware at the same time.
> 
> Please could you explain this some more. What firmware?

It's the firmware of our ethernet devices.

> There some registers which are clear on read. They don't work when you
> have multiple entities reading them.

I'm not trying to multiple access the I2C registers, but these registers cannot
be accessed by other interfaces in the process of reading complete information
each time. So there is a semaphore needed that locks up the entire read process.