On Wed, Jun 20, 2018 at 10:39:16AM -0700, Ray Jui wrote: > Hi Guenter/Rob, > > Kindly let me know how you want to proceed with this? > If I recall correctly, the patch series does not add a new problem but merely exposes one. Is my recollection correct ? If so, maybe we should just add a note somewhere indicating what might be wrong and otherwise apply the series. Does this make sense ? Guenter > Thanks, > > Ray > > On 6/6/2018 4:39 PM, Ray Jui wrote: > > > > > >On 6/6/2018 9:33 AM, Rob Herring wrote: > >>On Wed, Jun 6, 2018 at 11:19 AM, Guenter Roeck <linux@xxxxxxxxxxxx> > >>wrote: > >>>On 06/05/2018 12:41 PM, Rob Herring wrote: > >>>> > >>>>On Mon, May 28, 2018 at 11:01:32AM -0700, Ray Jui wrote: > >>>>> > >>>>>Consolidate two SP805 binding documents "arm,sp805.txt" and > >>>>>"sp805-wdt.txt" into "arm,sp805.txt" that matches the naming of the > >>>>>desired compatible string to be used > >>>>> > >>>>>Signed-off-by: Ray Jui <ray.jui@xxxxxxxxxxxx> > >>>>>--- > >>>>> .../devicetree/bindings/watchdog/arm,sp805.txt | 27 > >>>>>++++++++++++++----- > >>>>> .../devicetree/bindings/watchdog/sp805-wdt.txt | 31 > >>>>>---------------------- > >>>>> 2 files changed, 20 insertions(+), 38 deletions(-) > >>>>> delete mode 100644 > >>>>>Documentation/devicetree/bindings/watchdog/sp805-wdt.txt > >>>> > >>>> > >>>>Would be good to get a ACK from FSL/NXP person on this. It looks to me > >>>>like the driver fetches the wrong clock as it gets the first one and > >>>>the > >>>>driver really wants 'wdog_clk'. In any case, their dts files should be > >>>>updated. > >>>> > >>> > >>>This is really confusing, since he deleted file lists apb_pclk first. > >>>Does the watchdog driver need apb_pclk or wdog_clk ? That isn't clear > >>>to me. > >>>arch/arm64/boot/dts/hisilicon/hi3660.dtsi only provides apb_pclk, or at > >>>least > >>>it says so. > >> > >>Note that that clock source is 32KHz. That is obviously a mistake > >>because no one clocks their bus/register interface at 32KHz. Someone > >>just filled in something that happened to work. > >> > >>>The fsl dts files all have apb_pclk first. > >> > >>It's all kind of a mess, but fortunately one we should be able to > >>clean-up. > >> > > > >It is indeed a mess. Note the SP805 driver only derive one clock from DT, > >and that's not done based on name. As a result, the first clock defined in > >DT will be fetched and the rate calculation will be carried out based on > >that clock rate. > > > >I assumed the clock entries and their names defined in the binding > >document are just placeholders, at least for the 2nd clock. > > > >Based on how the current driver is, the first clock needs to be the > >WDOGCLK for things to work properly. > > > >According to the SP805 TRM, APB clock is the PCLK, that drives the bus for > >register access. > > > >The relationship between WDOGCLK and PCLK is defined as: > > > >- the rising edges of WDOGCLK must be synchronous and > >balanced with a rising edge of PCLK > > > >- the WDOGCLK frequency cannot be greater than the PCLK > >frequency > > > >>The compatible string changes too, but AMBA bus devices don't actually > >>use the compatible string as they use the ID registers to match. I > >>suppose some other OS could do things differently. Worth the risk to > >>clean-up IMO. > >> > >>> > >>>Either case, why are two clocks asked for in the first place ? Are there > >>>situations where the second clock is actually used/useful ? > >> > >>For clocks, the bus needs "apb_pclk" and the driver just gets the > >>first clock. The driver is obviously going to want the functional > >>clock that determines the counter rate. That should > >> > >>Primecell peripherals are about the only ones that have clear specs > >>WRT clock inputs. Yet we've still managed to screw them up. There are > >>2 clocks in the spec, so the DT has (or should have) 2 clocks. > >> > >>Rob > >> > > > >Let me know how you guys want to proceed with this? > > > >Thanks, > > > >Ray > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
