Re: [PATCH v4] mfd: syscon: Add non-DT support

Dong Aisheng
2013-02-22T09:19:51Z

On Fri, Feb 22, 2013 at 09:11:53AM +0000, Arnd Bergmann wrote:
> On Friday 22 February 2013, Thierry Reding wrote:
> > On Fri, Feb 22, 2013 at 03:13:12PM +0800, Dong Aisheng wrote:
> > > On Fri, Feb 22, 2013 at 11:01:18AM +0400, Alexander Shiyan wrote:
> > > > > On Thu, Feb 21, 2013 at 07:29:02PM +0400, Alexander Shiyan wrote:
> > > > > > This patch allow using syscon driver from the platform data, i.e.
> > > > > > possibility using driver on systems without oftree support.
> > > > > > For search syscon device from the client drivers,
> > > > > > "syscon_regmap_lookup_by_pdevname" function was added.
> > > > > >
> > > > > > Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> > > > >
> > > > > [...]
> > > > >
> > > > > > + syscon->base = devm_ioremap_resource(dev, res);
> > > > > > + if (!syscon->base)
> > > > >
> > > > > Is this correct?
> > > >
> > > > Hmm, of course IS_ERR should be used here...
> > > > v5?
> > > >
> > >
> > > Yes.
> > > >From here:
> > > https://lkml.org/lkml/2013/1/21/140
> > > It seems it is.
> >
> > Yes, devm_ioremap_resource() never returns NULL. You always need to
> > check the returned pointer with IS_ERR(). The value that you return
> > should be extracted from the pointer with PTR_ERR().
> >
>
> Well, devm_ioremap_resource also tries to request the resource, which
> as someone (Dong or Shawn?) pointed out, we should not do for the imx6q
> case. I think this has to be reverted to platform_get_resource
> and dev_ioremap.
>

Yes, i did not see detailed devm_ioremap_resource implementation,
but if it requests the resource then right, it may fail on imx6q due to
request overlapped resources.

Regards
Dong Aisheng