On Mon, Mar 09, 2015 at 04:27:11PM -0400, Peter Hurley wrote: > Changes from v2: > * remainder of unapplied series > * Changed the title and commit log for > "serial: earlycon: Allow earlycon params with name only" to > "serial: earlycon: Skip parse_options() for empty string" per Rob's > comment. > > Changes from v1: > * rebased on and requires "console: Fix console name size mismatch" > > > Hi Greg & Andrew, > > This patch series implements: > 1. console-definable (aka extensible) matching > 2. generic earlycon-to-console handoff via extensible matching > 3. arch/prom support for direct earlycon > > > Extensible console matching > > Extensible console matching enables the console itself to define the > conditions for a "command line" match. This mimics the design of > device matching in the driver model. Two important use-cases which this > feature enables are generic earlycon-to-console handoff and support > for driver migration. > > Earlycon-to-console handoff was implemented in 2007. Console command > lines of the form: > console=uart,io,0x3f8,115200n8 > start an earlycon and later allow the 8250 driver console to takeover. > Unfortunately this implementation requires direct coupling between > the earlycon and the console and is facilitated by ugly hacks like > editing the console command line in-place. > > Extensible console matching allows the 8250 driver to directly match > that console command line instead, and enables other serial drivers > to trivially support console handoff themselves. > > In addition, extensible console matching allows a new driver to > provide support for a different driver's console. This requirement > stems from needing to minimize breakage when migrating serial drivers. > Since many devices are based on the original 8250/16550 designs > but sometimes have features incompatible with the existing 8250 driver > support, the initial driver is often standalone. When/if the standalone > driver is migrated to the 8250 driver, the problem of console names in > the command line remains. Extensible console matching enables a simple > migration path. > > > Direct earlycon > > This feature enables arches and proms to start an earlycon directly, > rather than requiring an "earlycon=" command line parameter. > Devicetree can already do this via the 'linux,stdout-path' property, > but arch and prom code requires direct coupling to the serial driver. > > This support is implemented by judicious refactoring and the same > construct that devicetree and early_param use: a link table containing > the necessary information (name and setup() function) to find and > bind the appropriate earlycon "driver". > > > NB: I combined these two features in this series because their > implementations heavily overlap in the same source files. All now queued up, thanks. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
