On Wed, 2015-04-15 at 16:42 -0700, Andy Lutomirski wrote: > On Wed, Apr 15, 2015 at 3:38 PM, Andy Walls <awalls@xxxxxxxxxxxxxxxx> wrote: > > > > IMO the right solution would be to avoid ioremapping the whole bar at > startup. Instead ioremap pieces once the driver learns what they are. > This wouldn't have any of these problems -- you'd ioremap() register > regions and you'd ioremap_wc() the framebuffer once you find it. If > there are regions of unknown purpose, just don't map them all. > > Would this be feasible? Feasible? Maybe. Worth the time and effort for end-of-life, convential PCI hardware so I can have an optimally performing X display on a Standard Def Analog TV screen? Nope. I don't have that level of nostalgia. We sort of know where some things are in the MMIO space due to experimentation and past efforts examining the firmware binary. Documentation/video4linux/cx2341x/fw-*.txt documents some things. The driver code actually codifies a little bit more knowledge. The driver code for doing transfers between host and card is complex and fragile with some streams that use DMA, other streams that use PIO, digging VBI data straight out of card memory, and scatter-gather being broken on newer firmwares. Playing around with ioremapping will be hard to get right and likely cause something in the code to break for the primary use case of the ivtv supported cards. Regards, Andy -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
