Hi Jacopo, On Thu, Oct 5, 2017 at 9:48 AM, jacopo mondi <jacopo@xxxxxxxxxx> wrote: > On Wed, Oct 04, 2017 at 05:54:46PM +0200, Geert Uytterhoeven wrote: >> On Wed, Oct 4, 2017 at 5:40 PM, Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> wrote: >> > The system clock described by extal_clk is reported to have a frequency >> > of 13.333 Mhz and is correctly described by gr-peach device tree. >> > >> > However, when enabling a RIIC device the following error is reported by >> > drivers/i2c/busses/i2c-riic.c >> > >> > "invalid parent clk (33332500). Must be 33325000Hz" >> > >> > As RIIC devices have a clock source obtained by dividing by 12 the >> > system clock, the resulting value is not accepted by the driver >> > (which clearly states not to support any frequency except the reported >> > 33325000Hz one). >> > >> > Hence, reduce the system clock accuracy to a value which makes >> > frequencies obtained through division accepted by RIIC driver. >> > >> > Please note that other r7s72100 boards, such as Genmai, report the same >> > "reduced accuracy" frequency, even if their external clock sources are >> > effectively 13.333Mhz as gr-peach one. >> > >> > Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> >> >> There's no need to do this, Chris already proposed a fix, cfr. >> "[PATCH v2] i2c: riic: remove fixed clock restriction" >> (https://www.spinics.net/lists/linux-renesas-soc/msg18573.html). > > Oh that's even better! > Do you see any value in augmenting the frequency resolution in Genmai > DTS then? The Genmai documentation says EXTAL is 13.33 MHz (which matches r7s72100-genmai.dts) everywhere, except in the schematics, where it says 13.3333 MHz. Sigh... The difference is slightly larger than 100 ppm, so still insignificant, I think. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
