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

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Date:   Tue, 12 Jun 2018 16:51:38 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        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 12/06/18 16:24, Sudeep Holla wrote:
> On Tue, Jun 12, 2018 at 3:55 PM, Srinivas Kandagatla
> <srinivas.kandagatla@...aro.org> wrote:
>> GICR_WAKER can be a secured register, check this before accessing it
>> as its done in power management code.
>>
>> Without this patch Qualcomm DB820c board crashes.
>>
> 
> Are you sure this is the one causing the crash ?
> 
Yep, am 100% sure its the write in gic_enable_redist(). Very first zero 
write to GICR_WAKER is the one which is crashing my system.

If I add return before writing then I can boot my system fine.

Not sure why writes are not ignored?

Also why does other parts of the code have checks while accessing this 
register?

thanks,
srini

> As per GIC specification:
> "When GICD_CTLR.DS==1, this register is always accessible.
>   When GICD_CTLR.DS==0, this is a Secure register. This register is RAZ/WI
>   to Non-secure accesses."
> 
> 
> --
> Regards,
> Sudeep
>