linux-kernel - Re: [PATCH] irqchip/gic-v3: do not access GICR

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Date:   Wed, 13 Jun 2018 11:53:36 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        open list <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org,
        "Nayak, Rajendra" <rnayak@...eaurora.org>,
        bjorn.andersson@...aro.org, sboyd@...nel.org
Subject: Re: [PATCH] irqchip/gic-v3: do not access GICR_WAKER if its secured
 register.



On 13/06/18 09:45, Sudeep Holla wrote:
> On Wed, Jun 13, 2018 at 9:21 AM, Srinivas Kandagatla
> <srinivas.kandagatla@...aro.org> wrote:
>>
>>
>> On 12/06/18 17:34, Marc Zyngier wrote:
>>>
>>> I suggest you find out how the GIC has been integrated on this
>>> platform. If you take a fault on accessing this register, this very
>>> much looks like an integration bug, and it should be quirked as such.
>>
>> Thanks for the suggestion, This is a bug in the firmware which is
>> restricting access to this register. We have been working around this bug
>> for more than 2 years due to this. Now this platform support is in mainline
>> and We/I have no hope that this will be fixed in near future atleast for
>> this platform.
>>
> 
>  From what you are saying, you were aware of the firmware bug for 2 years as
> you had work-around from then. I wish the firmware had come up with the fix
> in those lost 2 years. I understand if it was discovered now, but that doesn't
> seem to be the case here.
> 
> Firmware fixes are now becoming inevitable, so the attitude that firmware can't
> be fixed has to slowing change. I am not saying I am against the quirk, but in
> general I have seen the firmware support of QCOM parts are really bad. I waited
> for almost 2 years for PSCI firmware on previous dragonboard where developer
> are trying to upstream some feature.
I agree with you!

We did wait for more than 2 years for firmware to be fixed. But it never 
happened and very little hopes to get it fixed.

I did try the quirk based on GICD_IIDR and I could boot linus master on 
DB820c!

I will send it out as RFC soon.

thanks,
srini
> 
> --
> Regards,
> Sudeep
>