linux-kernel - Re: [PATCH v2 1/7] arm: firmware: Check firmware is running or not

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Date:	Mon, 02 Jun 2014 15:05:54 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Tomasz Figa <tomasz.figa@...il.com>
Cc:	Kukjin Kim <kgene.kim@...sung.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Tomasz Figa <t.figa@...sung.com>,
	Sachin Kamat <sachin.kamat@...aro.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH v2 1/7] arm: firmware: Check firmware is running or not


Hi,

On Monday, June 02, 2014 02:51:14 PM Tomasz Figa wrote:
> Hi,
> 
> On 02.06.2014 14:35, Bartlomiej Zolnierkiewicz wrote:
> > From: Kyungmin Park <kyungmin.park@...sung.com>
> > 
> > To support multi-platform, it needs to know it's running under secure
> > OS or not.  Sometimes it needs to access physical address by SMC calls.
> > 
> > e.g.,
> >         if (firmware_run()) {
> >                 addr = physical address;
> >         } else {
> >                 addr = virtual address;
> >         }
> > 
> >         call_firmware_ops(read_address, addr, &value);
> 
> Hmm, I don't understand the code above. It first asks whether the
> firmware is available and then calls a firmware operation anyway
> (assuming that firmware is available regardless of the check above)...
> 
> I don't like the idea of this function, because we have designed the
> firmware API to not require this kind of checks. Instead, you just call
> whatever firmware operation you need and if it returns -ENOSYS you need
> to fallback to legacy (firmware-less) way of doing it.
> 
> Could you provide your use case for which this doesn't work?

Please take a look at patch #7.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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