On 01/07/2016 04:40 AM, Przemyslaw Marczak wrote:
The present implementation of __of_translate_address() taken from the Linux, is designed for translate bus/child address mappings by using 'ranges' property - and it doesn't allow for checking an address for a device's node with zero size-cells.
The 'size-cells > 0' is required for bus/child address mapping, but is not required for non-memory mapped address, e.g.: I2C chip. Then when we need only raw 'reg' property's value.
Since the I2C device address goes to a single-cell reg property, support for that case is welcome, but currently calling dev_get_addr() for I2C device will return 'FDT_ADDR_T_NONE', and print the warning:
warning: __of_translate_address: Bad cell count for 'some-dev'
This patch takes the wrong approach.
It simply doesn't make sense to /attempt/ to translate an I2C address into an MMIO address space. It's a nonsensical operation; no such translation is possible under any circumstances because I2C and MMIO addresses mean completely different things and simply can't be translated to each-other.
Rather than making this nonsensical operation succeed in a way that gives the desired no-op result, the nonsensical operation simply shouldn't be performed in the first place.