Message-ID: <c2dadf51-666f-72f6-7687-731f281ed7d6@alliedtelesis.co.nz>
Date:   Mon, 24 Aug 2020 22:04:00 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "paulus@...ba.org" <paulus@...ba.org>,
        "tiago.brusamarello@...acom.ind.br" 
        <tiago.brusamarello@...acom.ind.br>
CC:     "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: fsl_espi errors on v5.7.15


On 20/08/20 9:08 am, Chris Packham wrote:
>
> On 19/08/20 6:15 pm, Heiner Kallweit wrote:
>> On 19.08.2020 00:44, Chris Packham wrote:
>>> Hi Again,
>>>
>>> On 17/08/20 9:09 am, Chris Packham wrote:
>>>
>>>> On 14/08/20 6:19 pm, Heiner Kallweit wrote:
>>>>> On 14.08.2020 04:48, Chris Packham wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I'm seeing a problem with accessing spi-nor after upgrading a T2081
>>>>>> based system to linux v5.7.15
>>>>>>
>>>>>> For this board u-boot and the u-boot environment live on spi-nor.
>>>>>>
>>>>>> When I use fw_setenv from userspace I get the following kernel logs
>>>>>>
>>>>>> # fw_setenv foo=1
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>>>> fsl_espi ffe110000.spi: Transfer done but rx/tx fifo's aren't empty!
>>>>>> fsl_espi ffe110000.spi: SPIE_RXCNT = 1, SPIE_TXCNT = 32
>>>>>> fsl_espi ffe110000.spi: Transfer done but rx/tx fifo's aren't empty!
>>>>>> fsl_espi ffe110000.spi: SPIE_RXCNT = 1, SPIE_TXCNT = 32
>>>>>> fsl_espi ffe110000.spi: Transfer done but rx/tx fifo's aren't empty!
>>>>>> fsl_espi ffe110000.spi: SPIE_RXCNT = 1, SPIE_TXCNT = 32
>>>>>> ...
>>>>>>
>>>>> This error reporting doesn't exist yet in 4.4. So you may have an 
>>>>> issue
>>>>> under 4.4 too, it's just not reported.
>>>>> Did you verify that under 4.4 fw_setenv actually has an effect?
>>>> Just double checked and yes under 4.4 the setting does get saved.
>>>>>> If I run fw_printenv (before getting it into a bad state) it is 
>>>>>> able to
>>>>>> display the content of the boards u-boot environment.
>>>>>>
>>>>> This might indicate an issue with spi being locked. I've seen related
>>>>> questions, just use the search engine of your choice and check for
>>>>> fw_setenv and locked.
>>>> I'm running a version of fw_setenv which includes
>>>> https://gitlab.denx.de/u-boot/u-boot/-/commit/db820159 so it shouldn't
>>>> be locking things unnecessarily.
>>>>>> If been unsuccessful in producing a setup for bisecting the 
>>>>>> issue. I do
>>>>>> know the issue doesn't occur on the old 4.4.x based kernel but 
>>>>>> that's
>>>>>> probably not much help.
>>>>>>
>>>>>> Any pointers on what the issue (and/or solution) might be.
>>> I finally managed to get our board running with a vanilla kernel. With
>>> corenet64_smp_defconfig I occasionally see
>>>
>>>     fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>
>>> other than the message things seem to be working.
>>>
>>> With a custom defconfig I see
>>>
>>>     fsl_espi ffe110000.spi: Transfer done but SPIE_DON isn't set!
>>>     fsl_espi ffe110000.spi: Transfer done but rx/tx fifo's aren't 
>>> empty!
>>>     fsl_espi ffe110000.spi: SPIE_RXCNT = 1, SPIE_TXCNT = 32
>>>     ...
>>>
>>> and access to the spi-nor does not work until the board is reset.
>>>
>>> I'll try and pick apart the differences between the two defconfigs.
>
> I now think my earlier testing is invalid. I have seen the problem 
> with either defconfig if I try hard enough. I had convinced myself 
> that the problem was CONFIG_PREEMPT but that was before I found 
> boot-to-boot differences with the same kernel.
>
> It's possible that I'm chasing multiple issues with the same symptom.
>
> The error I'm most concerned with is in the sequence
> 1. boot with old image
> 2. write environment
> 3. boot with new image
> 4. write environment
> 5. write fails and environment is corrupted
>
> After I recover the system things sometimes seem fine. Until I repeat 
> the sequence above.
>
>> Also relevant may be:
>> - Which dts are you using?
> Custom but based heavily on the t2080rdb.
>> - What's the spi-nor type, and at which frequency are you operating it?
> The board has several alternate parts for the spi-nor so the dts just 
> specifies compatible = "jedec,spi-nor" the actual chip detected on the 
> board I have is "n25q032a (4096 Kbytes)". The dts sets 
> spi-max-frequency = <10000000> I haven't measured the actual frequency 
> on the bus.
>> - Does the issue still happen if you lower the frequency?
> I did play around with the frequency initially but I should probably 
> give that another go now that I have a better reproduction method.

Playing around with the frequency didn't help.

One thing that I've found is that the problem appears to be that I end 
up with extra bytes in the RX FIFO. If I add code to drain the RX FIFO 
then the system is able to keep accessing the spi-nor (albeit with some 
noisy logs).

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