On Thu, Oct 2, 2014 at 2:42 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > On 10/01/2014 08:12 PM, Stephen Warren wrote: >> On 10/01/2014 11:54 AM, jonsmirl@xxxxxxxxx wrote: >>> On Wed, Oct 1, 2014 at 1:26 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: >> ... >>>> We've been over all this again and again and again. >>>> >>>> AAAARRRRRGGGGGGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH! >>>> >>>> All solutions provided sofar are both tons more complicated, then the >>>> simple solution of simply having the simplefb dt node declare which >>>> clocks it needs. And to make things worse all of them sofar have >>>> unresolved issues (due to their complexity mostly). >>>> >>>> With the clocks in the simplefb node, then all a real driver has to do, >>>> is claim those same clocks before unregistering the simplefb driver, >>>> and everything will just work. >>>> >>>> Yet we've been discussing this for months, all because of some >>>> vague worries from Thierry, and *only* from Thierry that this will >>>> make simplefb less generic / not abstract enough, while a simple >>>> generic clocks property is about as generic as things come. >> >> Note: I haven't been following this thread, and really don't have the time to get involved, but I did want to point out one thing: >> >> As I think I mentioned very early on in this thread, one of the big concerns when simplefb was merged was that it would slowly grow and become a monster. As such, a condition of merging it was that it would not grow features like resource management at all. That means no clock/regulator/... support. It's intended as a simple stop-gap between early platform bringup and whenever a real driver exists for the HW. If you need resource management, write a HW-specific driver. The list archives presumably have a record of the discussion, but I don't know the links off the top of my head. If nobody >> other than Thierry is objecting, presumably the people who originally objected simply haven't noticed this patch/thread. I suppose it's possible they changed their mind. >> >> BTW, there's no reason that the simplefb code couldn't be refactored out into a support library that's used by both the simplefb we currently have and any new HW-specific driver. It's just that the simplefb binding and driver shouldn't grow. > > The whole reason why we want to use simplefb is not just to get things > running until HW specific driver is in place, but also to have early console > output (to help debugging boot problems on devices without a serial console), > in a world where most video drivers are build as loadable modules, so we > won't have video output until quite late into the boot process. You need both. 1) temporary early boot console -- this is nothing but an address in RAM and the x/y layout. The character set from framebuffer is built into the kernel. The parallel to this is early-printk and how it uses the UARTs without interrupts. This console vaporizes late in the boot process -- the same thing happens with the early printk UART driver. EARLYPRINTK on the command line enables this. 2) a device specific driver -- this sits on initrd and it loaded as soon as possible. The same thing happens with the real UART driver for the console. CONSOLE= on the command line causes the transition. There is an API in the kernel to do this transition, I believe it is called set_console() but it's been a while. > > This is also the reason why we're working on adding hdmi console support > to u-boot in the first place, to debug boot problems. > > So the whole "write a HW specific driver" answer just does not cut it. Just > like we have vgacon / efifb on x86, we need something similar on ARM, and > since ARM does not have a generic hw interface like vga, we need a firmware > solution like efifb. > > So as said the whole "write a HW specific driver" just will not work, so > that means using something like simplefb. Now I can take simplefb, copy > it to rename it to firmwarefb or ubootfb or something, and then add the clocks > support, but that is just silly. > > You indicate that you don't have the time for this discussion, and I note that > there is no MAINTAINERS entry for drivers/video/fbdev/simplefb.c . So how about > the following, I pick up drivers/video/fbdev/simplefb.c maintainership, adding > MAINTAINERS entry for it with my name in it. Then as the maintainer it will be > my responsibility (and in my own benefit) to stop this from growing into > a monster ? > > To me that seems better then adding a new drivers/video/fbdev/firmwarefb.c > which will be just a copy with the clocks added. > > Regards, > > Hans -- Jon Smirl jonsmirl@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
