From this link and the Installation Instructions tab we see a "dn" version specified, but we can't seem to download it.

Drivers & software for HP LaserJet P2055 Printer series

http://h20565.www2.hp.com/portal/site/hpsc/template.PAGE/public/psi/swdDetails/?sp4ts.oid=3662058&spf_p.tpst=swdMain&spf_p.prp_swdMain=wsrp-navigationalState%3Didx%253D2%257CswItem%253Dlj_66014_11%257CswEnvOID%253D4063%257CitemLocale%253D%257CswLang%253D%257Cmode%253D4%257Caction%253DdriverDocument&javax.portlet.begCacheTok=com.vignette.cachetoken&javax.portlet.endCacheTok=com.vignette.cachetoken

whereas this community site has assured us since March 2014 that the instructions are wrong:

P2055dn Firmware

http://h30499.www3.hp.com/t5/Printers-LaserJet/P2055dn-Firmware/td-p/6397969#.VCG5NmMiN8E

The update seems to work fine and we get a happy face :-)

The "P2050" is a little frightening after all instructions were all "P2055dn only" ...