linux-kernel - Re: [PATCH v3] mfd: lpc_ich: Fix resource request for [mem 0x00000000]

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Message-ID: <20121121163301.GA18738@sortiz-mobl>
Date:	Wed, 21 Nov 2012 17:33:01 +0100
From:	Samuel Ortiz <sameo@...ux.intel.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Peter Tyser <ptyser@...-inc.com>, linux-kernel@...r.kernel.org,
	Aaron Sierra <asierra@...-inc.com>
Subject: Re: [PATCH v3] mfd: lpc_ich: Fix resource request for [mem
 0x00000000]

Hi Peter,

On Mon, Nov 19, 2012 at 01:28:53PM -0500, Peter Hurley wrote:
> On Mon, 2012-11-19 at 18:46 +0100, Samuel Ortiz wrote:
> > Hi Peter,
> > 
> > On Fri, Nov 09, 2012 at 06:55:29AM -0500, Peter Hurley wrote:
> > > The older southbridges supported by the lpc_ich driver do not
> > > provide memory-mapped space of the root complex. The driver
> > > correctly avoids computing the iomem address in this case, yet
> > > submits a zeroed resource request anyway (via mfd_add_devices()).
> > > 
> > > Remove the iomem resource from the resource array submitted to the
> > > mfd core for the older southbridges.
> > > 
> > > Acked-by: Aaron Sierra <asierra@...-inc.com>
> > > Cc: Peter Tyser <ptyser@...-inc.com>
> > > Cc: Samuel Ortiz <sameo@...ux.intel.com>
> > > Signed-off-by: Peter Hurley <peter@...leysoftware.com>
> > > ---
> > > 
> > > v2: post-decrement to match existing style
> > >     retitle patch subject
> > > v3: respin as standalone patch
> > > 
> > >  drivers/mfd/lpc_ich.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/mfd/lpc_ich.c b/drivers/mfd/lpc_ich.c
> > > index a22544f..f507c09 100644
> > > --- a/drivers/mfd/lpc_ich.c
> > > +++ b/drivers/mfd/lpc_ich.c
> > > @@ -842,6 +842,9 @@ static int __devinit lpc_ich_init_wdt(struct pci_dev *dev,
> > >  		res = wdt_mem_res(ICH_RES_MEM_GCS);
> > >  		res->start = base_addr + ACPIBASE_GCS_OFF;
> > >  		res->end = base_addr + ACPIBASE_GCS_END;
> > > +	} else {
> > So I suppose there is no v3 for the iTCO ? If we're expecting all versions
> > after 1 to have a memory mapped region, we should have something like:
> > 
> > --- a/drivers/mfd/lpc_ich.c
> > +++ b/drivers/mfd/lpc_ich.c
> > @@ -830,7 +830,10 @@ static int __devinit lpc_ich_init_wdt(struct pci_dev
> > *dev,
> >          * we have to read RCBA from PCI Config space 0xf0 and use
> >          * it as base. GCS = RCBA + ICH6_GCS(0x3410).
> >          */
> > -       if (lpc_chipset_info[id->driver_data].iTCO_version == 2) {
> > +       if (lpc_chipset_info[id->driver_data].iTCO_version == 1) {
> > +               /* Don't register iomem for TCO ver 1 */
> > +               lpc_ich_cells[LPC_WDT].num_resources--;
> > +       } else {
> >                 pci_read_config_dword(dev, RCBABASE, &base_addr_cfg);
> >                 base_addr = base_addr_cfg & 0xffffc000;
> >                 if (!(base_addr_cfg & 1)) {
> 
> Hi Samuel,
> 
> I have no objection to your version.
I applied and pushed it to my for-next branch.

 
> FWIW, the iTCO_version field is exclusively a driver construct used to
> differentiate southbridges that support memory-mapped I/O to the TCO
> registers from those that only support port-based I/O. IOW, there's no
> intrinsic meaning to the values and could be represented with a bool
> type instead.
Right, that sounds like follow up patch material.

Cheers,
Samuel.

-- 
Intel Open Source Technology Centre
http://oss.intel.com/
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