[PATCH V2] spi: Update speed/mode on change

[Marek Vasut]

On 2/26/21 3:21 PM, Marek Vasut wrote:
> The spi_get_bus_and_cs() may be called on the same bus and chipselect
> with different frequency or mode. This is valid usecase, but the code
> fails to notify the controller of such a configuration change. Call
> spi_set_speed_mode() in case bus frequency or bus mode changed to let
> the controller update the configuration.
> 
> The problem can easily be triggered using the sspi command:
> => sspi 0:0 at 1000
> => sspi 0:0 at 2000
> Without this patch, both transfers happen at 1000 Hz. With this patch,
> the later transfer happens correctly at 2000 Hz.
> 
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Jagan Teki <jagan at amarulasolutions.com>
> Cc: Patrick Delaunay <patrick.delaunay at st.com>

This bugfix is still missing from upstream.