On 16.10.2013 11:48, Thierry Reding wrote:
On Tue, Oct 15, 2013 at 09:19:18AM -0600, Stephen Warren wrote:
Taking advantage of new functionality isn't the issue. The issue is whether a driver that was written purely to the spec of Tegra20 can successfully operate on the HW. If it can't, then the HW is not compatible with Tegra20. Terje's previous comments sounded like the HW is not backwards-compatible, although his more recent comments make it sound like only SW policy differences, which shouldn't be part of DT anyway.
Well, as good as I can tell it is backwards-compatible. I've been testing the code included in this series with the same simple test program that clears a rectangle on Tegra20, Tegra30 and Tegra114.
Furthermore our internal register specification files are identical, with the exception of some whitespace changes for all three generations. I think that qualifies as backwards-compatible?
A driver written for Tegra20 2D works with Tegra114 2D. Not necessarily vice versa, because Tegra114's driver can ask for higher clocks, or it might want to power gate 2D.
I mentioned earlier bringup activities. Perhaps Stephen took that in a way I didn't intend.
Terje