Quoting Radu Nicolae Pirea (2019-05-31 07:06:03) > > + remove_common_factor(&rate[1]); > > + dev_dbg(&drvdata->client->dev, > > + "PLL output frequency: %llu+%llu/%llu Hz\n", > > + rate[0], rate[1], rate[2]); > > + > > + return rate[0]; > > +} > > + > > +static long si5338_pll_round_rate(struct clk_hw *hw, unsigned long > > rate, > > + unsigned long *parent_rate) > > +{ > I think is a designs problem in clock subsystem. > Description of the function round_rate is this. > > @round_rate: Given a target rate as input, returns the closest rate > actually supported by the clock. The parent rate is an input/output > parameter. > > If given rate is unsigned long and the return value is long, we have a > problem. Return value can be an error value but can also be a 32 bit > frequency value that can be huge enoguh to set MSB bit and if MSB bit > is set, the return value is a negative value and will be considered > error code. > > In drivers/clk/clk.c, in function clk_core_determine_round_nolock, on > line 1199 is this sequence of code that checks if the value returned by > round_rate function is negative: > > } else if (core->ops->round_rate) { > rate = core->ops->round_rate(core->hw, req->rate, > &req->best_parent_rate); > if (rate < 0) > return rate; > > In drivers/clk/clk.c, in function clk_calc_new_rates, on line 1780, is > the next sequence of code that checks if > clk_core_determine_round_nolock returns a negative value: > > ret = clk_core_determine_round_nolock(core, &req); > if (ret < 0) > return NULL; > > and... if function clk_calc_new_rates returns NULL, in function > clk_core_set_rate_nolock from drivers/clk/clk.c, on line 2023, is the > next sequence of code that evaluates NULL, returned by > clk_calc_new_rates as -EINVAL > > top = clk_calc_new_rates(core, req_rate); > if (!top) > return -EINVAL; > > So... si5338_pll_round_rate can return 32 bit values like 2500000000 Hz > who have MSB bit set and are interpreted as error codes. > > Have someone a suggestion to fix this issue? >
Can you use the determine_rate clk op? It won't work for rounding outside of the framework though so things like clk_round_rate() still fail.