On Wed, Feb 24, 2016 at 01:21:51PM +0200, Tomi Valkeinen wrote: > On 24/02/16 12:46, Russell King - ARM Linux wrote: > > On Tue, Feb 23, 2016 at 02:45:30PM +0200, Tomi Valkeinen wrote: > >> My opinion is that the bootloader should be responsible for telling the > >> kernel what hardware there is on the board. For busses like PCI we have > >> proper probing mechanism with global unique identifiers for the devices, > >> and nothing is needed from the bootloader. > > > > Exactly, but that is _NOT_ the case here, because we're not talking > > about an on-board display. > > Ok, what is it then? I'm not familiar with the boards in question. > > When does a display become an on-board display? All the panels I have > can be disconnected quite easily, but I still consider them as on-board > displays. The difference to me is quite clear. If the connector is a flexi-strip or LVDS connector designed to be connected directly to a panel, it is not designed as a user connector, and the display can be regarded as part of the board: the connector probably isn't rated for a large number of mating cycles. If the connector is a board-edge external-unit connector, then the panel is not part of the board. In the case of Versatile, it's the latter: the connector is situated at the board edge, next to the serial port connectors, and is designed to connect to an external box housing the display. > > That argument does not stack up. Just because you've plugged in a > > network device does not mean that the kernel can drive it: the kernel > > needs a device specific driver, which is determined by looking at the > > IDs. There is no standard network driver PCI interface. > > Yes, but you can connect the network device to any board with a PCI bus > and it works. Here, if I'm not mistaken, the displays are built for this > single board, making them board specific. It only works because Linux has a rich array of network drivers supporting all that hardware, and the appropriate network driver is bound depending on the hardware ID of the card. If a new PCI network device comes out, it'll more likely than not require an update to a network driver to make it work. The displays are not built for "this single board" but for a family of boards: not only Versatile PB/AB, but also the Realview family of boards too. > But I cannot accept that as a general solution for all similar cases > going forward, especially when moving to DRM world, that's just bad SW > design. I think that's a matter of personal opinion, perspective and situation. What is good design today is not necessary good design yesterday or tomorrow. I thought we already ascertained that earlier in this discussion. :) -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- 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
