From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heikki Krogerus Subject: Re: [PATCH v3 09/11] serial: 8250_lpss: move Quark code from PCI driver Date: Wed, 4 May 2016 13:04:31 +0300 Message-ID: <20160504100431.GA15689@kuha.fi.intel.com> References: <1461764894-14891-1-git-send-email-andriy.shevchenko@linux.intel.com> <1461764894-14891-10-git-send-email-andriy.shevchenko@linux.intel.com> <1462354262.27858.153.camel@nexus-software.ie> <1462355477.27858.161.camel@nexus-software.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1462355477.27858.161.camel@nexus-software.ie> Sender: linux-kernel-owner@vger.kernel.org To: Bryan O'Donoghue Cc: Andy Shevchenko , Andy Shevchenko , Peter Hurley , "linux-serial@vger.kernel.org" , Vinod Koul , "linux-kernel@vger.kernel.org" , dmaengine , Greg Kroah-Hartman , "Puustinen, Ismo" List-Id: linux-serial@vger.kernel.org Hi Bryan, On Wed, May 04, 2016 at 10:51:17AM +0100, Bryan O'Donoghue wrote: > On Wed, 2016-05-04 at 12:42 +0300, Andy Shevchenko wrote: > > On Wed, May 4, 2016 at 12:31 PM, Bryan O'Donoghue > > wrote: > > > Andy, > > > > > > If you are going to start removing working PCI devices from the PCI > > > config table in favour of a shim in SERIAL_8250_LPSS then the very > > > minimum should be some sort of dependency link between > > > SERIAL_8250_LPSS > > > and CONFIG_SERIAL_8250_PCI in kconfig. > > > > > > A user could reasonably read the QRK datasheet - switch on > > > CONFIG_SERIAL_8250_PCI and then wonder why no console output > > > happened > > > on boot. S/he shouldn't have to know that devices were moved from > > > the > > > PCI driver to an LPSS shim driver or that the 8250_lpss driver now > > > needs to be selected instead of the intuitively correct 8250_pci > > > driver. > > > > That is taken care of since default is set to SERIAL_8250 (you even > > don't need to have PCI driver enabled!). > > Doesn't work for you? > > The default may be set to SERIAL_8250 but, without the QRK specific > entry in 8250_pci.c you won't get console output. > > So if you are going to remove the QRK entry from 8250_pci.c and stuff > it into 8250_lpss.c then 8250_lpss needs to be selected by > CONFIG_SERIAL_8250_PCI. > > Otherwise the person doing the config needs to know that stuff was > moved from one file to another - even though it's a PCI device (not an > LPSS/ACPI enumerated device) - which seems like an unreasonable level > of knowledge to assume on the part of the user. The only way the user get's to de-select CONFIG_SERIAL_8250_PCI or CONFIG_SERIAL_8250_LPSS is if S/he also selects CONFIG_EXPERT, and if S/he does that then we can assume S/he has the knowledge. I'm against binding these separated drivers to CONFIG_SERIAL_8250_PCI because doing that will very fast mean that we also remove the possibility to de-select CONFIG_SERIAL_8250_PCI when only, for example, CONFIG_SERIAL_8250_LPSS was wanted. Thanks, -- heikki