Re: [PATCH v3 5/5] spi: imx: drop useless member speed_hz from driver data struct

[Trent Piepho <tpiepho@xxxxxxxxxx>]

On Fri, 2018-11-30 at 07:47 +0100, Uwe Kleine-König wrote:
> The driver data's member variable just caches the transfer's speed_hz
> member. All users of the former now have access directly to the latter.
> So fix them to use the uncached value and remove the cache.

What should have been done with this is to compare the next transfer's
speed_hz to this cached value, and not preprogram the clock if it has
not changed.  Since usually it doesn't change between transfers.

spi_bus_clk caches the actual spi bus clock, which is often not exactly
the same as the transfer speed, so using it compare against the next
transfer doesn't work as well.