Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208AbbG2QXR (ORCPT ); Wed, 29 Jul 2015 12:23:17 -0400 Received: from xes-mad.com ([216.165.139.218]:55115 "EHLO xes-mad.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751206AbbG2QXQ (ORCPT ); Wed, 29 Jul 2015 12:23:16 -0400 Date: Wed, 29 Jul 2015 11:20:05 -0500 (CDT) From: Aaron Sierra To: Lee Jones Cc: Matt Fleming , Wim Van Sebroeck , linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, Mika Westerberg , Andy Shevchenko , Jean Delvare , Wolfram Sang , Matt Fleming , Peter Tyser , Samuel Ortiz Message-ID: <1571539887.303369.1438186805578.JavaMail.zimbra@xes-inc.com> In-Reply-To: <20150729153226.GB9319@x1> References: <1438004292-16382-1-git-send-email-matt@codeblueprint.co.uk> <20150728094643.GT14943@x1> <20150728110717.GH2492@codeblueprint.co.uk> <20150728113721.GU14943@x1> <72454140.319490.1438109162683.JavaMail.zimbra@xes-inc.com> <20150729073841.GF2284@x1> <2115196252.256986.1438181571315.JavaMail.zimbra@xes-inc.com> <20150729153226.GB9319@x1> Subject: Re: [PATCH 1/5] iTCO_wdt: Expose watchdog properties using platform data MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.52.16.65] X-Mailer: Zimbra 8.0.6_GA_5922 (ZimbraWebClient - FF39 (Linux)/8.0.6_GA_5922) Thread-Topic: iTCO_wdt: Expose watchdog properties using platform data Thread-Index: 0OiHenXON4FlfZqgjL5YYzc/AkMK8g== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4358 Lines: 107 > From: "Lee Jones" > Sent: Wednesday, July 29, 2015 10:32:26 AM > > On Wed, 29 Jul 2015, Aaron Sierra wrote: > > > > From: "Lee Jones" > > > Sent: Wednesday, July 29, 2015 2:38:41 AM > > > > > > On Tue, 28 Jul 2015, Aaron Sierra wrote: > > > > > > > > > > > @@ -933,7 +956,7 @@ gpe0_done: > > > > > > > > lpc_chipset_info[priv->chipset].use_gpio = ret; > > > > > > > > lpc_ich_enable_gpio_space(dev); > > > > > > > > > > > > > > > > - lpc_ich_finalize_cell(dev, &lpc_ich_cells[LPC_GPIO]); > > > > > > > > + lpc_ich_finalize_gpio_cell(dev); > > > > > > > > ret = mfd_add_devices(&dev->dev, PLATFORM_DEVID_AUTO, > > > > > > > > &lpc_ich_cells[LPC_GPIO], 1, NULL, 0, NULL); > > > > > > > > > > > > > > > > @@ -1007,7 +1030,10 @@ static int lpc_ich_init_wdt(struct > > > > > > > > pci_dev > > > > > > > > *dev) > > > > > > > > res->end = base_addr + ACPIBASE_PMC_END; > > > > > > > > } > > > > > > > > > > > > > > > > - lpc_ich_finalize_cell(dev, &lpc_ich_cells[LPC_WDT]); > > > > > > > > + ret = lpc_ich_finalize_wdt_cell(dev); > > > > > > > > + if (ret) > > > > > > > > + goto wdt_done; > > > > > > > > + > > > > > > > > ret = mfd_add_devices(&dev->dev, PLATFORM_DEVID_AUTO, > > > > > > > > &lpc_ich_cells[LPC_WDT], 1, NULL, 0, NULL); > > > > > > > > > > > > > > Why do you have an mfd_add_devices() call for each device? > > > > > > > > > > > > Good question. This call has been present since March 2012 when > > > > > > support > > > > > > was first added for iTCO_wdt in commit 887c8ec7219f ("watchdog: > > > > > > Convert > > > > > > iTCO_wdt driver to mfd model"). > > > > > > > > > > > > There's no good reason that I can see. Aaron? > > > > > > > > I chose to call mfd_add_devices() in each device init function > > > > because I thought it was the easiest way to avoid registering an > > > > incomplete/invalid MFD cell should an error occur during init. > > > > > > > > That way device registration wouldn't be an all-or-nothing affair. > > > > > > > > Doesn't mfd_add_devices() bail out after the first unsuccessful > > > > mfd to platform device translation? > > > > > > Right, as it should. > > > > > > Under what circumstance would an error occur and you'd wish to carry > > > on registering devices? > > > > Lee, > > > > The two devices that this driver is responsible for are conceptually > > independent; they simply are lumped together in one PCI device. No > > failure while preparing resources for the watchdog device should > > prevent the GPIO device from being registered. > > This makes me think that perhaps this isn't an MFD at all then? > > Perhaps I should invest some time to looking into that. > > > The most common real world circumstance that I experience is when a > > BIOS reserves resources associated with the GPIO device, thus > > preventing the GPIO resources (ICH_RES_GPE0 and/or ICH_RES_GPIO) from > > being fully prepared. > > > > I have not experienced issues with the watchdog device, but a similar > > issue would exist if the RCBA were disabled in a "v2" device. > > > > It seems like a dangerous change to simply attempt to register both > > of these devices with a single call, when one or both of them could > > be incomplete. > > > > Perhaps your real issue with this driver structure is that these > > cells are elements of a single lpc_ich_cells array for no clear > > reason. If each had a dedicated mfd_cell variable, would that be > > more acceptable to you? > > > > -static struct mfd_cell lpc_ich_cells[] = { > > +static struct mfd_cell lpc_ich_wdt_cell = { > > ... > > +static struct mfd_cell lpc_ich_gpio_cell = { > > > > That would eliminate the need for the lpc_cells enum, too. > > Yes, that would make more sense. Also consider using mfd_add_device() > instead of mfd_add_devices(), as you are only attempting registration > for a single device. > I can submit a patch the splits up the array elements, but I only see mfd_add_device() as a static function in mfd-core.c; Is that being exported in a development branch somewhere? -Aaron S. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/