On Tuesday 17 January 2017 12:17 AM, David Lechner wrote: > On 01/16/2017 08:30 AM, Bartosz Golaszewski wrote: >> 2017-01-16 13:45 GMT+01:00 Sekhar Nori <nsekhar@xxxxxx>: >>> On Monday 16 January 2017 03:43 PM, Bartosz Golaszewski wrote: >>>> 2017-01-13 20:25 GMT+01:00 David Lechner <david@xxxxxxxxxxxxxx>: >>>>> >>>>> A clock multiplier property seems redundant if you are specifying a >>>>> clock. >>>>> It should be possible to get the rate from the clock to determine >>>>> which >>>>> multiplier is needed. >>>>> >>>> >>>> I probably should have named it differently. This is not a multiplier >>>> of a clock derived from PLL0 or PLL1. Instead it's a value set by >>>> writing to the Port PHY Control Register (MPY bits) of the SATA >>>> controller that configures the multiplier for the external low-jitter >>>> clock. On the lcdk the signals (REFCLKP, REFCLKN) are provided by >>>> CDCM61001 (SATA OSCILLATOR component on the schematics). >>>> >>>> I'll find a better name and comment the property accordingly. >>>> >>>> FYI: the da850 platform does not use the common clock framework, so I >>>> don't specify the clock property on the sata node in the device tree. >>>> Instead I add the clock lookup entry in patch [01/10]. This is >>>> transparent for AHCI which can get the clock as usual by calling >>>> clk_get() in ahci_platform_get_resources(). >>> >>> I think David's point is that the SATA_REFCLK needs to be modeled as a >>> actual clock input to the IP. You should be able to get the rate using >>> clk_get_rate() and make the MPY bits calculation depending on the >>> incoming rate. >>> >>> You should be able to model the clock even when not using common clock >>> framework. >>> >>> DA850 AHCI does not use a con_id at the moment (it assumes a single >>> clock), and that needs to change. >>> >> >> It's true that once davinci gets ported (is this planned?) to using >> the common clock framework, we could just create a fixed-clock node in >> da850-lcdk for the SATA oscillator, so the new property is redundant. >> > > I have some commits[1] where I started on converting da850 to use the > common clock framework. But, I don't know anything about other davinci > family devices, so I don't think I could really take that to completion > without lots of help. I can help with testing, reviewing and filling in any missing information. But I wont have time to write the code itself. > > [1]: https://github.com/dlech/ev3dev-kernel/commits/wip-20160509 I see that you have made a copy of the keystone PSC driver. I think you will need pretty strong reasons to not use the same driver with some customization for DaVinci. >> What I don't get is how should I model a clock that is not >> configurable and is board-specific? Is hard-coding the relevant rate >> in da850.c with a huge FIXME the right way? > > In arch/arm/mach-davinci/usb-da8xx.c, there is a "usb_refclkin" that is > very similar to the situation with the sata refclk. You could do > something like this to register the clock... > > --- > > diff --git a/arch/arm/mach-davinci/devices-da8xx.c > b/arch/arm/mach-davinci/devices-da8xx.c > index c2457b3..790efce9 100644 > --- a/arch/arm/mach-davinci/devices-da8xx.c > +++ b/arch/arm/mach-davinci/devices-da8xx.c > @@ -1023,6 +1023,34 @@ int __init da8xx_register_spi_bus(int instance, > unsigned num_chipselect) > } > > #ifdef CONFIG_ARCH_DAVINCI_DA850 > + > +static struct clk sata_refclkin = { > + .name = "sata_refclkin", > + .set_rate = davinci_simple_set_rate, > +}; > + > +static struct clk_lookup sata_refclkin_lookup = > + CLK(NULL, "sata_refclkin", &sata_refclkin); > + > +/** > + * da8xx_register_sata_refclkin - register SATA_REFCLKIN clock > + * > + * @rate: The clock rate in Hz > + */ > +int __init da850_register_sata_refclkin(int rate) > +{ > + int ret; > + > + sata_refclkin.rate = rate; > + ret = clk_register(&sata_refclkin); > + if (ret) > + return ret; > + > + clkdev_add(&sata_refclkin_lookup); > + > + return 0; > +} > + > static struct resource da850_sata_resources[] = { > { > .start = DA850_SATA_BASE, > @@ -1055,8 +1083,11 @@ static struct platform_device da850_sata_device = { > > int __init da850_register_sata(unsigned long refclkpn) > { > - /* please see comment in drivers/ata/ahci_da850.c */ > - BUG_ON(refclkpn != 100 * 1000 * 1000); > + int err; > + > + err = da850_register_sata_refclkin(refclkpn); > + if (err) > + return err; > > return platform_device_register(&da850_sata_device); > } > > --- > > Then to get things working from device tree, add this... > > --- > > diff --git a/arch/arm/mach-davinci/da8xx-dt.c > b/arch/arm/mach-davinci/da8xx-dt.c > index d2be194..b54bdd6 100644 > --- a/arch/arm/mach-davinci/da8xx-dt.c > +++ b/arch/arm/mach-davinci/da8xx-dt.c > @@ -60,6 +60,14 @@ static void __init da850_init_machine(void) > pr_warn("%s: registering USB 1.1 PHY clock failed: %d", > __func__, ret); > > + if (of_machine_is_compatible("ti,da850-evm") || > + of_machine_is_compatible("ti,da850-lcdk")) { > + ret = da850_register_sata_refclkin(100000000); > + if (ret) > + pr_warn("%s: registering SATA_REFCLK clock > failed: %d", > + __func__, ret); > + } > + > of_platform_default_populate(NULL, da850_auxdata_lookup, NULL); > davinci_pm_init(); > pdata_quirks_init(); This approach is fine. Thanks, Sekhar -- 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
