Re: [PATCH v2 4/6] ARM: tegra: rework fuse.c

From: Stephen Warren
Date: Tue Jan 07 2014 - 15:47:19 EST

On 01/07/2014 07:10 AM, Peter De Schrijver wrote:
> On Mon, Jan 06, 2014 at 09:50:42PM +0100, Stephen Warren wrote:
>> On 12/24/2013 06:32 AM, Peter De Schrijver wrote:
>>> Reduce fuse.c to the minimum functionality required for the early bootstages.
>>> Also export tegra_read_straps() for use by the fuse driver.

>>> diff --git a/arch/arm/mach-tegra/fuse.c b/arch/arm/mach-tegra/fuse.c

>>> -int tegra_sku_id;
>>> -int tegra_cpu_process_id;
>>> -int tegra_core_process_id;
>>> int tegra_chip_id;
>>> -int tegra_cpu_speedo_id; /* only exist in Tegra30 and later */
>>> -int tegra_soc_speedo_id;
>>> enum tegra_revision tegra_revision;
>> It's a bit odd to remove most of this, but leave a few parts hanging
>> around. Wouldn't it be better to the drivers/misc/fuse code to export
>> this, so that /all/ the fuse logic was there, rather than part of it
>> being left over in arch/arm/? We'll need to fix that up anyway when we
>> start using these globals on ARMv8, so may as well get it right now.
>> Also, I rather think that the new drivers/misc/fuse code shouldn't be a
>> module or driver, so that we can guarantee it's always there to provide
>> the globals and that they are initialized early enough...
> tegra_revision is used in tegra_dt_init() to initialize soc_dev_attr->revision
> Hence this needs to be available before the fuse driver is initialized.

Yes, the same for tegra_chip_id too.

My point is: Why not move all the globals into the fuse driver, and make
an early call to that fuse driver to initialize all these globals.
Basically, rework this patch series to simply move the code to
drivers/misc/fuse/, and keep initializing it by function call rather
than as a driver probe(). The code can still scan DT to get the required
reg/clock/... resources, in a similar fashion to e.g. the Tegra timer or
cpufreq drivers IIRC. Perhaps the sysfs exports could be associated with
a driver still though - just initialize the globals early?
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