On 12/06/19 6:08 PM, Raul Rangel wrote: > On Wed, Jun 12, 2019 at 04:09:47PM +0300, Adrian Hunter wrote: >> On 10/06/19 9:53 PM, Raul E Rangel wrote: >>> The O2 controller supports 8-bit EMMC access. mmc_select_bus_width() >>> will be used to determine if the MMC supports 8-bit or 4-bit access. >> >> The problem is that the bit indicates a host controller capability, not how >> many data lines there actually are on the board. Will this break something >> that does not have 8 lines? > > So I asked the controller vendor about that: >> The capability shows the host controller can support 1,4,and 8 bit bus >> data transfer but it also depends on if HW can support it. Driver or FW >> should implement the bus testing procedure that is defined in A.6.3.a >> in JESD84-B51 spec to decide the real bus width that is supported in HW. > > This seems to be what `mmc_select_bus_width()` is doing. Good point. Can you add this information to the commit message and add a comment in the code. > > I don't actually have any 4-bit hardware to test with though. > > Thanks for the review! >
