From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH 3/3] i2c: i801: Do not add ICH_RES_IO_SMI if PMC device is not present Date: Tue, 25 Feb 2020 16:40:47 +0200 Message-ID: <20200225144047.GC2667@lahna.fi.intel.com> References: <20200225123802.88984-1-mika.westerberg@linux.intel.com> <20200225123802.88984-4-mika.westerberg@linux.intel.com> <2dec872e-26fb-eefc-5606-cfb1bf55d02e@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <2dec872e-26fb-eefc-5606-cfb1bf55d02e-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: linux-watchdog-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck Cc: Jean Delvare , Wim Van Sebroeck , Wolfram Sang , Martin Volf , Andy Shevchenko , Jarkko Nikula , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-hwmon-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Tue, Feb 25, 2020 at 06:21:16AM -0800, Guenter Roeck wrote: > On 2/25/20 4:38 AM, Mika Westerberg wrote: > > Martin noticed that nct6775 driver does not load properly on his system > > in v5.4+ kernels. The issue was bisected to commit b84398d6d7f9 ("i2c: > > i801: Use iTCO version 6 in Cannon Lake PCH and beyond") but it is > > likely not the culprit because the faulty code has been in the driver > > already since commit 9424693035a5 ("i2c: i801: Create iTCO device on > > newer Intel PCHs"). So more likely some commit that added PCI IDs of > > recent chipsets made the driver to create the iTCO_wdt device on Martins > > system. > > > > The issue was debugged to be PCI configuration access to the PMC device > > that is not present. This returns all 1's when read and this caused the > > iTCO_wdt driver to accidentally request resourses used by nct6775. > > > > Fix this by checking that the PMC device is there and only then populate > > the iTCO_wdt ICH_RES_IO_SMI resource. Since the resource is now optional > > the iTCO_wdt driver should continue to work on recent systems without it. > > > > Link: https://lore.kernel.org/linux-hwmon/CAM1AHpQ4196tyD=HhBu-2donSsuogabkfP03v1YF26Q7_BgvgA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org/ > > Fixes: 9424693035a5 ("i2c: i801: Create iTCO device on newer Intel PCHs") > > Reported-by: Martin Volf > > Signed-off-by: Mika Westerberg > > --- > > drivers/i2c/busses/i2c-i801.c | 45 +++++++++++++++++++++-------------- > > 1 file changed, 27 insertions(+), 18 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > > index ca4f096fef74..7fa58375bd4b 100644 > > --- a/drivers/i2c/busses/i2c-i801.c > > +++ b/drivers/i2c/busses/i2c-i801.c > > @@ -1519,7 +1519,7 @@ static DEFINE_SPINLOCK(p2sb_spinlock); > > static struct platform_device * > > i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev, > > - struct resource *tco_res) > > + struct resource *tco_res, size_t nres) > > { > > struct resource *res; > > unsigned int devfn; > > @@ -1563,7 +1563,7 @@ i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev, > > res->flags = IORESOURCE_MEM; > > return platform_device_register_resndata(&pci_dev->dev, "iTCO_wdt", -1, > > - tco_res, 3, &spt_tco_platform_data, > > + tco_res, nres + 1, &spt_tco_platform_data, > > Does this work as intended ? It still adds ICH_RES_MEM_OFF at index 2, > but if there is no SMI resource it will only pass two sets of resources > to the wdt driver, one of which (the SMI resource) would be empty, > ie have start == NULL and size == 0. Good point that would not work as expected. I'll fix this one in the next version.