From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751557AbcBKRMp (ORCPT ); Thu, 11 Feb 2016 12:12:45 -0500 Received: from mail-wm0-f50.google.com ([74.125.82.50]:35913 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbcBKRMn (ORCPT ); Thu, 11 Feb 2016 12:12:43 -0500 Date: Thu, 11 Feb 2016 17:12:38 +0000 From: Lee Jones To: Peter Tyser Cc: Antoine Tenart , linus.walleij@linaro.org, gnurou@gmail.com, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Mika Westerberg Subject: Re: [PATCH 2/3] mfd: lpc_ich: use a correct mask for the GPIO base address Message-ID: <20160211171238.GJ20693@x1> References: <1453566729-30220-1-git-send-email-antoine.tenart@free-electrons.com> <1453566729-30220-3-git-send-email-antoine.tenart@free-electrons.com> <20160125124444.GJ3368@x1> <1453738070.1770.74.camel@xes-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1453738070.1770.74.camel@xes-inc.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 25 Jan 2016, Peter Tyser wrote: > > On Mon, 2016-01-25 at 12:44 +0000, Lee Jones wrote: > > On Sat, 23 Jan 2016, Antoine Tenart wrote: > > > > > The GPIO base address is read from the GPIOBASE register. The first > > > bit must be cleared as it can be hardwired to 1 to represent the i/o > > > space. Other bits are either containing the base address of are > > > reserved. They should not be cleared as all the chipsets do not have > > > the same reserved bits. > > > > > > Signed-off-by: Antoine Tenart tenart@free-electrons.com> > > > --- > > > drivers/mfd/lpc_ich.c | 5 ++++- > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > Applied, thanks. > > Is it possible to hold off on the application of the change Lee? Patch unapplied. > > > diff --git a/drivers/mfd/lpc_ich.c b/drivers/mfd/lpc_ich.c > > > index b514f3cf140d..f13a5ded3958 100644 > > > --- a/drivers/mfd/lpc_ich.c > > > +++ b/drivers/mfd/lpc_ich.c > > > @@ -921,7 +921,10 @@ static int lpc_ich_init_gpio(struct pci_dev *dev) > > > gpe0_done: > > > /* Setup GPIO base register */ > > > pci_read_config_dword(dev, priv->gbase, &base_addr_cfg); > > > - base_addr = base_addr_cfg & 0x0000ff80; > > > + > > > + /* Clear the i/o flag */ > > > + base_addr = base_addr_cfg & ~BIT(0); > > > + > > > Does this patch work around an issue you are seeing? Looking at the Bay > Trail EDS, the GPIO base address register looks like it should work fine > with the original code (it uses 0xff00 as a mask for the address, and > reserves 0x80 which reads as a 0). Also, Bay Trail bit 1 is an enable > flag, which this patch wouldn't mask off. Eg if the BIOS enables the GPIO > controller and sets the enable bit, I think things would break with this > patch. > > It's also scary to not mask off the reserved bits on other Intel chipsets - > you're assuming they all read as 0 and I'm not sure if this is true or > not. The patch also doesn't make the same change to the other base > register reads either, and ideally they'd be kept in sync. > > Seems like things should be left as-is, or use an accurate chip-specific > mask. > > I'd leave as-is personally. Like Mika mentioned, Baytrail GPIO should > already be supported elsewhere, which should make this change unnecessary. > > Regards, > Peter -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog