linux-kernel - Re: [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform reset

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Message-ID: <alpine.DEB.2.02.1602220631300.3418@utopia.booyaka.com>
Date:	Mon, 22 Feb 2016 06:31:56 +0000 (UTC)
From:	Paul Walmsley <paul@...an.com>
To:	Kishon Vijay Abraham I <kishon@...com>
cc:	Sekhar Nori <nsekhar@...com>, Suman Anna <s-anna@...com>,
	d-gerlach@...com, Tony Lindgren <tony@...mide.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>, richardcochran@...il.com,
	Russell King <linux@....linux.org.uk>,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform
 reset

Kishon,

On Mon, 22 Feb 2016, Kishon Vijay Abraham I wrote:

> Sekhar,
> 
> On Thursday 18 February 2016 07:51 PM, Sekhar Nori wrote:
> > On Friday 12 February 2016 10:50 PM, Suman Anna wrote:
> >> Sekhar,
> >> Will you be following up with above suggestion since Kishon is gonna be out?
> > 
> > Alright, noticed this action for me :) Went through the thread, and 
> > looks like this is what we want to see?
> > 
> > Thanks,
> > Sekhar
> > 
> > ---8<---
> > From e3ba368f2235e1bf38a22ba8ea4e5c12aaafda19 Mon Sep 17 00:00:00 2001
> > Message-Id: <e3ba368f2235e1bf38a22ba8ea4e5c12aaafda19.1455803758.git.nsekhar@...com>
> > From: Sekhar Nori <nsekhar@...com>
> > Date: Thu, 18 Feb 2016 16:49:56 +0530
> > Subject: [PATCH 1/1] ARM: DRA7: hwmod: Add custom reset handler for PCIeSS
> > 
> > Add a custom reset handler for DRA7x PCIeSS. This
> > handler is required to deassert PCIe hardreset lines
> > after they have been asserted.
> > 
> > This enables the PCIe driver to access registers after
> > PCIeSS has been runtime enabled without having to
> > deassert hardreset lines itself.
> > 
> > With this patch applied, used lspci to make sure
> > connected PCIe device enumerates on DRA74x and DRA72x
> > EVMs.
> > 
> > Signed-off-by: Sekhar Nori <nsekhar@...com>
> > ---
> > Applies to tag for-v4.6/omap-hwmod-a of Paul W's tree.
> > 
> >  arch/arm/mach-omap2/omap_hwmod_7xx_data.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> > 
> > diff --git a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c
> > index b61355e2a771..252b74633e31 100644
> > --- a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c
> > +++ b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c
> > @@ -1526,8 +1526,31 @@ static struct omap_hwmod dra7xx_ocp2scp3_hwmod = {
> >   *
> >   */
> >  
> > +/*
> > + * As noted in documentation for _reset() in omap_hwmod.c, the stock reset
> > + * functionality of OMAP HWMOD layer does not deassert the hardreset lines
> > + * associated with an IP automatically leaving the driver to handle that
> > + * by itself. This does not work for PCIeSS which needs the reset lines
> > + * deasserted for the driver to start accessing registers.
> > + *
> > + * We use a PCIeSS HWMOD class specific reset handler to deassert the hardreset
> > + * lines after asserting them.
> > + */
> > +static int dra7xx_pciess_reset(struct omap_hwmod *oh)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < oh->rst_lines_cnt; i++) {
> > +		omap_hwmod_assert_hardreset(oh, oh->rst_lines[i].name);
> > +		omap_hwmod_deassert_hardreset(oh, oh->rst_lines[i].name);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static struct omap_hwmod_class dra7xx_pciess_hwmod_class = {
> >  	.name	= "pcie",
> > +	.reset	= dra7xx_pciess_reset,
> >  };
> 
> Thanks for the patch.

Could you please test the bind/unbind functionality just to make sure it 
works?

thanks

- Paul