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From: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
To: "wsa@kernel.org" <wsa@kernel.org>,
	Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Cc: "andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>,
	"andriy.shevchenko@linux.intel.com" 
	<andriy.shevchenko@linux.intel.com>,
	"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/4] P2040/P2041 i2c recovery erratum
Date: Thu, 20 May 2021 03:36:58 +0000	[thread overview]
Message-ID: <ae39c62a-7dc7-81f5-ea10-edfdbf905e9d@alliedtelesis.co.nz> (raw)
In-Reply-To: <20210512150118.GA1004@ninjato>


On 13/05/21 3:01 am, wsa@kernel.org wrote:
>>> I've been doing my recent work with a P2040 and prior to that I did test
>>> out the recovery on a T2081 (which isn't documented to have this
>>> erratum) when I was re-working the driver. The "new" recovery actually
>>> seems better but I don't have a reliably faulty i2c device so that's
>>> only based on me writing some code to manually trigger the recovery
>>> (using the snippet below) and observing it with an oscilloscope.
>> You don't need a faulty device, just an aborted I2C read/write op.
> If you can wire GPIOs to the bus, you can use the I2C fault injector:
>
> 	Documentation/i2c/gpio-fault-injection.rst
>
> There are already two "incomplete transfer" injectors.
>
Just giving this thread a poke. I have been looking at my options for 
triggering an i2c recovery but haven't really had time to do much. I 
think the best option given what I've got access to is a modified SFP 
that grounds the SDA line but I need to find a system where I can attach 
an oscilloscope (should be a few of these in the office when I can get 
on-site).

I can confirm that when manually triggered the existing recovery and the 
new erratum workaround produce what I'd expect to observe on an 
oscilloscope.

I haven't explored Joakim's alternative recovery but I don't think that 
should hold up these changes, any improvement to the existing recovery 
can be done later as a follow-up.

WARNING: multiple messages have this Message-ID (diff)
From: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
To: "wsa@kernel.org" <wsa@kernel.org>,
	Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"andriy.shevchenko@linux.intel.com"
	<andriy.shevchenko@linux.intel.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v3 0/4] P2040/P2041 i2c recovery erratum
Date: Thu, 20 May 2021 03:36:58 +0000	[thread overview]
Message-ID: <ae39c62a-7dc7-81f5-ea10-edfdbf905e9d@alliedtelesis.co.nz> (raw)
In-Reply-To: <20210512150118.GA1004@ninjato>


On 13/05/21 3:01 am, wsa@kernel.org wrote:
>>> I've been doing my recent work with a P2040 and prior to that I did test
>>> out the recovery on a T2081 (which isn't documented to have this
>>> erratum) when I was re-working the driver. The "new" recovery actually
>>> seems better but I don't have a reliably faulty i2c device so that's
>>> only based on me writing some code to manually trigger the recovery
>>> (using the snippet below) and observing it with an oscilloscope.
>> You don't need a faulty device, just an aborted I2C read/write op.
> If you can wire GPIOs to the bus, you can use the I2C fault injector:
>
> 	Documentation/i2c/gpio-fault-injection.rst
>
> There are already two "incomplete transfer" injectors.
>
Just giving this thread a poke. I have been looking at my options for 
triggering an i2c recovery but haven't really had time to do much. I 
think the best option given what I've got access to is a modified SFP 
that grounds the SDA line but I need to find a system where I can attach 
an oscilloscope (should be a few of these in the office when I can get 
on-site).

I can confirm that when manually triggered the existing recovery and the 
new erratum workaround produce what I'd expect to observe on an 
oscilloscope.

I haven't explored Joakim's alternative recovery but I don't think that 
should hold up these changes, any improvement to the existing recovery 
can be done later as a follow-up.

  reply	other threads:[~2021-05-20  3:37 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 21:20 [PATCH v3 0/4] P2040/P2041 i2c recovery erratum Chris Packham
2021-05-11 21:20 ` Chris Packham
2021-05-11 21:20 ` [PATCH v3 1/4] dt-bindings: i2c: mpc: Add fsl,i2c-erratum-a004447 flag Chris Packham
2021-05-11 21:20   ` [PATCH v3 1/4] dt-bindings: i2c: mpc: Add fsl, i2c-erratum-a004447 flag Chris Packham
2021-05-11 21:20 ` [PATCH v3 2/4] powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P2041 i2c controllers Chris Packham
2021-05-11 21:20   ` [PATCH v3 2/4] powerpc/fsl: set fsl, i2c-erratum-a004447 " Chris Packham
2021-05-26  1:02   ` [PATCH v3 2/4] powerpc/fsl: set fsl,i2c-erratum-a004447 " Michael Ellerman
2021-05-26  1:02     ` Michael Ellerman
2021-05-11 21:20 ` [PATCH v3 3/4] powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P1010 " Chris Packham
2021-05-11 21:20   ` [PATCH v3 3/4] powerpc/fsl: set fsl, i2c-erratum-a004447 " Chris Packham
2021-05-26  1:02   ` [PATCH v3 3/4] powerpc/fsl: set fsl,i2c-erratum-a004447 " Michael Ellerman
2021-05-26  1:02     ` Michael Ellerman
2021-05-11 21:20 ` [PATCH v3 4/4] i2c: mpc: implement erratum A-004447 workaround Chris Packham
2021-05-11 21:20   ` Chris Packham
2021-05-11 22:10 ` [PATCH v3 0/4] P2040/P2041 i2c recovery erratum Joakim Tjernlund
2021-05-11 22:10   ` Joakim Tjernlund
2021-05-12  1:48   ` Chris Packham
2021-05-12  1:48     ` Chris Packham
2021-05-12  8:57     ` Joakim Tjernlund
2021-05-12  8:57       ` Joakim Tjernlund
2021-05-12 15:01       ` wsa
2021-05-12 15:01         ` wsa
2021-05-20  3:36         ` Chris Packham [this message]
2021-05-20  3:36           ` Chris Packham
2021-05-25 18:49     ` wsa
2021-05-25 18:49       ` wsa
2021-05-25 18:53 ` Wolfram Sang
2021-05-25 18:53   ` Wolfram Sang
2021-05-26  1:02   ` Michael Ellerman
2021-05-26  1:02     ` Michael Ellerman
2021-05-27 19:53     ` Wolfram Sang
2021-05-27 19:53       ` Wolfram Sang

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