5 Aug
2014
5 Aug
'14
8:43 a.m.
On Sun, 2014-08-03 at 05:32 +0300, Siarhei Siamashka wrote:
We can safely remove it, because none of the currently supported boards uses these features.
The existing implementation had multiple problems:
- unnecessary code duplication between sun4i/sun5i/sun7i
- ZQ calibration was never initiated explicitly, and could be only triggered by setting the highest bit in the 'zq' parameter in the 'dram_para' struct (this was never actually done for any of the known Allwinner devices).
- even if the ZQ calibration could be started, no attempts were made to wait for its completion, or checking whether the default automatically initiated ZQ calibration is still in progress
- ODT was only ever enabled on sun4i, but not on sun5i/sun7i
Additionally, SDR_IOCR was set to 0x00cc0000 only on sun4i. There are some hints in the Rockchip Linux kernel sources, indicating that these bits are related to the automatic I/O power down feature, which is poorly understood on sunxi hardware at the moment. Avoiding to set these bits on sun4i too does not seem to have any measurable/visible impact.
The impedance and ODT configuration code will be re-introdeced in one of the next comits.
Signed-off-by: Siarhei Siamashka siarhei.siamashka@gmail.com
Acked-by: Ian Campbell ijc@hellion.org.uk