On 13/11/2020 15:21, Claudiu Beznea wrote: > There are regulators who's min selector is not zero. Selectors loops > (looping b/w zero and regulator::desc::n_voltages) might throw errors > because invalid selectors are used (lower than > regulator::desc::linear_min_sel). For this situations validate selectors > against regulator::desc::linear_min_sel. After this commit was merged, I noticed a regression in the DFLL (CPU clock source) on Tegra124. The DFLL driver (drivers/clk/tegra/clk-dfll.c) calls regulator_list_voltage() in a loop to determine the selector for a given voltage (see function find_vdd_map_entry_exact()). Currently, the DFLL driver queries the number of voltages provided by the regulator by calling regulator_count_voltages() and then starting from 0, iterates through the number of voltages to find the selector value for the voltage it is looking for by calling regulator_list_voltage(). It assumes that any negative value returned by calling regulator_list_voltage() is an error and this will cause the loop up to terminate. In this case the regulator in question is the as3722 and the linear_min_sel for this regulator is 1 and so when the DFLL driver calls regulator_list_voltage() with a selector value of 0 it now returns a negative error code, as expected by this change, and this terminates the loop up in the DFLL driver. So I can clearly see why this is happening and I could fix up the DFLL driver to avoid this. Before doing so, I wanted to ask if that is the correct fix here, because it seems a bit odd that regulator_count_voltages() returns N voltages, but if the min selector value is greater than 0, then actually there are less than N. However, changing the number of voltages supported by the regulator to be N - linear_min_sel does not make sense either because then we need to know the linear_min_sel in order to determine the first valid voltage. In case of the as3722, the value 0 means that the regulator is powered down. So it is a valid setting and equates to 0 volts at the output AFAICT. Please let me know your thoughts are the correct way to fix this up. Thanks Jon -- nvpublic
