Alan Cox wrote: >> polling for media change which involves reading maybe a few tens of >> bytes. The overhead of doing those using PIO wouldn't be too much more >> than the cost of writing CDBs out. It would help more if we can cut >> down the number of commands used for testing media changed event (on my >> to do list). > > Actually the overhead is foul on some laptops as the command byte write > wakes up the controller, which then whirrs away for a bit recovering its > status before deciding to give us an answer. Yeah, but that happens whether DMA is used or not. Probably what's needed is disabling media presence polling according to power profile. >> Does module parameter / sysfs node sound good enough to you? > > You mean like the existing "dma" one we already have which lets you turn > on/off atapi DMA and could be extended with another bit so we went from > > 1 - disk > 2 - cd > 4 - cf > > to > > 1 - disk > 2 - cd (basic commands) > 4 - cf > 8 - cd (all) > > > (The idea being that its ordered so troubleshooting almost always comes > down to 1,3 - or 1,3,7 with this). So we have 99.9% of this Basically, yes but I think it would be nice to be able to change the value on the fly. > As to the sysfs node for per device setup that makes sense as does fixing > the support to allow users to force a mode of their choice, and putting > in the geometry fields. Yeap. -- tejun - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
