linux-kernel - Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly

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Date:   Thu, 13 Sep 2018 18:35:38 +0200
From:   Cédric Le Goater <clg@...d.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>,
        Joel Stanley <joel@....id.au>, linux-aspeed@...ts.ozlabs.org,
        Vernon Mauery <vernon.mauery@...ux.intel.com>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-i2c@...r.kernel.org, jarkko.nikula@...ux.intel.com,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        James Feist <james.feist@...ux.intel.com>
Subject: Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq
 events properly

On 09/13/2018 05:57 PM, Guenter Roeck wrote:
> On Thu, Sep 13, 2018 at 05:48:59PM +0200, Cédric Le Goater wrote:
>> On 09/13/2018 03:33 PM, Guenter Roeck wrote:
> [ ... ]
>>>>>   /*
>>>>>    * The state machine needs some refinement. It is only used to track
>>>>>    * invalid STOP commands for the moment.
>>>>> @@ -188,7 +215,7 @@ static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, uint64_t value)
>>>>>   {
>>>>>       bus->cmd &= ~0xFFFF;
>>>>>       bus->cmd |= value & 0xFFFF;
>>>>> -    bus->intr_status = 0;> +    bus->intr_status &= I2CD_INTR_RX_DONE;
>>>>
>>>> it deserves a comment to understand which scenario we are trying to handle.
>>>>    
>>>
>>> Ok. FWIW, I wonder if intr_status should be touched here in the first place,
>>> but I neither have the hardware nor a datasheet, so I don't know if any bits
>>> are auto-cleared.
>>
>> I just pushed a patch on my branch with some more explanation : 
>>
>> 	https://github.com/legoater/qemu/commits/aspeed-3.1
>>
> That seems to suggest that none of the status bits auto-clears, and that
> the above code clearing intr_status should be removed entirely.
> Am I missing something ?

You are right. I just pushed another version of the previous patch with this 
new hunk :

@@ -188,7 +200,6 @@ static void aspeed_i2c_bus_handle_cmd(As
 {
     bus->cmd &= ~0xFFFF;
     bus->cmd |= value & 0xFFFF;
-    bus->intr_status = 0;
 
     if (bus->cmd & I2CD_M_START_CMD) {
         uint8_t state = aspeed_i2c_get_state(bus) & I2CD_MACTIVE ?


The QEMU palmetto and witherspoon machines seem to behave fine. Can you give 
it a try ?

Thanks,

C.