Hi James, Am Freitag, 14. November 2014, 15:32:09 schrieb James Hogan: > Commit 79c6ab509558 (clk: divider: add CLK_DIVIDER_READ_ONLY flag) in > v3.16 introduced the CLK_DIVIDER_READ_ONLY flag which caused the > recalc_rate() and round_rate() clock callbacks to be omitted. > > However using this flag has the unfortunate side effect of causing the > clock recalculation code when a clock rate change is attempted to always > treat it as a pass-through clock, i.e. with a fixed divide of 1, which > may not be the case. Child clock rates are then recalculated using the > wrong parent rate. > > Therefore instead of dropping the recalc_rate() and round_rate() > callbacks, alter clk_divider_bestdiv() to always report the current > divider as the best divider so that it is never altered. > > For me the read only clock was the system clock, which divided the PLL > rate by 2, from which both the UART and the SPI clocks were divided. > Initial setting of the UART rate set it correctly, but when the SPI > clock was set, the other child clocks were miscalculated. The UART clock > was recalculated using the PLL rate as the parent rate, resulting in a > UART new_rate of double what it should be, and a UART which spewed forth > garbage when the rate changes were propagated. > > Signed-off-by: James Hogan <[email protected]> > Cc: Mike Turquette <[email protected]> > Cc: Heiko Stuebner <[email protected]> > Cc: Thomas Abraham <[email protected]> > Cc: Tomasz Figa <[email protected]> > Cc: Max Schwarz <[email protected]> > Cc: <[email protected]> # v3.16+
Yep, your solution is much better I think. Reviewed-by: Heiko Stuebner <[email protected]> Heiko -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
