Message-ID: <1430846944.5506.34.camel@spandruv-DESK3.jf.intel.com>
Subject: Re: [PATCH v1] x86: punit_atom: punit device state debug driver
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
        linux-kernel@vger.kernel.org, pebolle@tiscali.nl,
        Borislav Petkov <bp@alien8.de>
Date: Tue, 05 May 2015 10:29:04 -0700
In-Reply-To: <20150502060050.GA10932@gmail.com>
References: <1430521630-19788-1-git-send-email-srinivas.pandruvada@linux.intel.com>
	 <1430521630-19788-2-git-send-email-srinivas.pandruvada@linux.intel.com>
	 <20150502060050.GA10932@gmail.com>
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Hi Ingo and Thomas,
One question inside on location.
On Sat, 2015-05-02 at 08:00 +0200, Ingo Molnar wrote:
> * Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote:
> 
> > The patch adds a debug driver, which dumps the power states
> > of all the North complex (NC) devices. This debug interface is
> > useful to figure out the NC IPs which blocks the S0ix
> > transitions on the platform. This is extremely useful during
> > enabling PM on customer platforms and derivatives.
> 
> Looks useful.
> 
> > This submission not a complete rewrite from the original
> > submission from Kumar P, Mahesh <mahesh.kumar.p.intel.com>.
> > https://lkml.org/lkml/2014/11/5/367
> 
> This sentence does not parse. Did you mean 'is a complete rewrite'?
> 
> > +config PUNIT_ATOM_DEBUG
> > +	tristate "ATOM Punit debug driver"
> > +	depends on DEBUG_FS
> > +	select IOSF_MBI
> > +	---help---
> > +	  This is a debug driver, which gets the power states
> > +	  of all Punit North Complex devices.The power states of
> > +	  each IP is exposed as part of the debugfs interface.
> 
> What is an 'IP'?
> 
> Also:
> 
>       s/devices.The
>        /devices. The
> 
> > +
> >  endmenu
> > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> > index cdb1b70..2ecbd55 100644
> > --- a/arch/x86/kernel/Makefile
> > +++ b/arch/x86/kernel/Makefile
> > @@ -110,6 +110,7 @@ obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
> >  obj-$(CONFIG_TRACING)			+= tracepoint.o
> >  obj-$(CONFIG_IOSF_MBI)			+= iosf_mbi.o
> >  obj-$(CONFIG_PMC_ATOM)			+= pmc_atom.o
> > +obj-$(CONFIG_PUNIT_ATOM_DEBUG)		+= punit_atom_debug.o
> >  
> >  ###
> >  # 64 bit specific files
> > diff --git a/arch/x86/kernel/punit_atom_debug.c b/arch/x86/kernel/punit_atom_debug.c
> 
> Please put this somewhere suitable in arch/x86/platform/.
I moved this to arch/x86/platform/intel-mid, but punit is much more part
of common core atom soc platform. This can have both mobile and PC like
platform. What about creating arch/x86/platform/intel-atom-common, and
add there?

Thanks,
Srinivas
> 
> > +/*
> > + * Intel SOC Punit device state debug driver
> > + * Copyright (c) 2015, Intel Corporation.
> 
> Would be nice to add a blurb about what 'Intel SOC Punit' systems are. 
> There doesn't seem to be anything in the kernel source about it, so 
> you have a golden opportunity here.
> 
> > +#define PUNIT_PORT		0x04
> > +#define PWRGT_STATUS		0x61 /* Power gate status reg */
> > +#define VED_SS_PM0		0x32 /* Subsystem config/status Video */
> > +#define ISP_SS_PM0		0x39 /* Subsystem config/status ISP */
> > +#define MIO_SS_PM		0x3B /* Subsystem config/status MIO */
> > +#define SSS_SHIFT		24
> > +#define RENDER_POS		0
> > +#define MEDIA_POS		2
> > +#define VLV_DISPLAY_POS		6
> > +#define CHT_DSP_SSS		0x36 /* Subsystem config/status DSP */
> > +#define CHT_DSP_SSS_POS		16
> 
> All the magic constants need some explanation for humans, not just 
> some.
> 
> > +static const struct punit_device punit_device_byt[] = {
> > +	{ "GFX RENDER", PWRGT_STATUS, RENDER_POS },
> > +	{ "GFX MEDIA", PWRGT_STATUS, MEDIA_POS },
> > +	{ "DISPLAY", PWRGT_STATUS, VLV_DISPLAY_POS },
> > +	{ "VED", VED_SS_PM0, SSS_SHIFT},
> > +	{ "ISP", ISP_SS_PM0, SSS_SHIFT},
> > +	{ "MIO", MIO_SS_PM, SSS_SHIFT},
> > +	{ NULL}
> > +};
> > +
> > +static const struct punit_device punit_device_cht[] = {
> > +	{ "GFX RENDER", PWRGT_STATUS, RENDER_POS },
> > +	{ "GFX MEDIA", PWRGT_STATUS, MEDIA_POS },
> > +	{ "DSP", CHT_DSP_SSS,  CHT_DSP_SSS_POS },
> > +	{ "VED", VED_SS_PM0, SSS_SHIFT},
> > +	{ "ISP", ISP_SS_PM0, SSS_SHIFT},
> > +	{ "MIO", MIO_SS_PM, SSS_SHIFT},
> > +	{ NULL}
> > +};
> 
> Please align such initialization tables vertically, like you did here:
> 
> > +static const struct file_operations punit_dev_state_ops = {
> > +	.open		= punit_dev_state_open,
> > +	.read		= seq_read,
> > +	.llseek		= seq_lseek,
> > +	.release	= single_release,
> > +};
> 
> 
> > +	punit_dbg_file = debugfs_create_dir("punit_atom", NULL);
> > +	if (!punit_dbg_file)
> > +		return -ENXIO;
> > +
> > +	dev_state = debugfs_create_file("dev_state", S_IFREG | S_IRUGO,
> > +					 punit_dbg_file, NULL,
> > +					 &punit_dev_state_ops);
> 
> So why isn't something that is declaradly a power state dump, called 
> "power_state" or "dev_power_state"?
> 
> > +MODULE_AUTHOR("Kumar P, Mahesh <mahesh.kumar.p.intel.com>");
> > +MODULE_DESCRIPTION("Driver for Punit devices states debugging");
> > +MODULE_LICENSE("GPL v2");
> 
> Btw., you can have multiple MODULE_AUTHOR() lines, so you can credit
> yourself as well. Take a look at drivers/net/wireless/at76c50x-usb.c's 
> MODULE_AUTHOR() for grins.
> 
> Thanks,
> 
> 	Ingo


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