On Fri, Aug 17, 2018 at 04:06:06PM +0530, dkota@xxxxxxxxxxxxxx wrote:My bad; i mean, you to comment on below explanation on using cur_speed_hz instead of clk_get_rate().
Could you please clarify on below query.
I'm not seeing any further questions in your e-mail?
+ mas->cur_speed_hz = spi_slv->max_speed_hz;
Why can't you use clk_get_rate() instead? Or call clk_set_rate() with
the rate you want the master clk to run at and then divide that down
> Not sure I follow, the intention is to run the controller clock based on
> the slave's max frequency.
That's good. The problem I see is that we have to specify the max
frequency in the controller/bus node, and also in the child/slave
It should only need to be specified in the slave node, so making the
cur_speed_hz equal the max_speed_hz is problematic. The current speed
the master should be determined by calling clk_get_rate().
We don't require that the slaves all individually set a speed since it
gets a bit redundant, it should be enough to just use the default the
controller provides. A bigger problem with this is that the driver
never see a transfer which doesn't explicitly have a speed set as the
core will ensure something is set, open coding this logic in every
driver would obviously be tiresome.